Method and apparatus for requesting complete information or partial information on aps in transmission mld in wireless lan system

ABSTRACT

Provided are a method and apparatus for requesting complete information or partial information on access points (APs) in a transmitting multi-link device (MLD) in a wireless local area network (WLAN) system. Specifically, a receiving MLD transmits a probe request frame to the transmitting MLD through a first link. The receiving MLD receives a probe response frame from the transmitting MLD through the first link. The transmitting MLD includes a first transmitting station (STA) operating in the first link and a second transmitting STA operating in a second link. The receiving MLD includes a first receiving STA operating in the first link and a second receiving STA operating in the second link. The probe request frame includes a profile field of the second receiving STA.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.17/527,403, filed on Nov. 16, 2021, which claims the benefit pursuant to35 U.S.C. § 119 (a) of Korean Patent Application No. 10-2020-0155785,filed on Nov. 19, 2020, the contents of which are all herebyincorporated by reference herein in their entirety.

BACKGROUND Field of the Disclosure

The present disclosure relates to a multi-link operation in a wirelesslocal area network (WLAN) system, and more particularly, to a method andapparatus for requesting complete information or partial information onaccess points (APs) in a transmitting multi-link device (MLD).

Related Art

A wireless local area network (WLAN) has been improved in various ways.For example, the IEEE 802.11ax standard proposed an improvedcommunication environment using orthogonal frequency division multipleaccess (OFDMA) and downlink multi-user multiple input multiple output(DL MU MIMO) techniques.

The present specification proposes a technical feature that can beutilized in a new communication standard. For example, the newcommunication standard may be an extreme high throughput (EHT) standardwhich is currently being discussed. The EHT standard may use anincreased bandwidth, an enhanced PHY layer protocol data unit (PPDU)structure, an enhanced sequence, a hybrid automatic repeat request(HARQ) scheme, or the like, which is newly proposed. The EHT standardmay be called the IEEE 802.11be standard.

In a new WLAN standard, an increased number of spatial streams may beused. In this case, in order to properly use the increased number ofspatial streams, a signaling technique in the WLAN system may need to beimproved.

SUMMARY

The present specification proposes a method and apparatus for requestingcomplete information or partial information on access points (APs) in atransmitting multi-link device (MLD) in a wireless local area network(WLAN) system.

An example of the present specification proposes a method of requestingcomplete information or partial information on APs in a transmittingMLD.

The present embodiment may be performed in a network environment inwhich a next-generation WLAN system (IEEE 802.11be or EHT WLAN system)is supported. The next-generation WLAN system is a WLAN system evolvedfrom an 802.11ax system, and may satisfy backward compatibility with the802.11ax system.

The present embodiment proposes a method and apparatus in which, when anon-AP station (STA) requests information on not a peer AP but other APsthrough a probe request frame, the probe request frame includes acomplete information profile subfield, so that whether the request is apartial information request or a complete information request isdetermined according to a value of the complete information profilesubfield. Herein, a transmitting MLD may correspond to an AP MLD, and areceiving MLD may correspond to a non-AP MLD. If the non-AP STA is afirst receiving STA, a first transmitting STA connected to the firstreceiving STA through a first link may be a peer AP, and second andthird transmitting STAs connected through other links may be other APs.

The receiving MLD transmits a probe request frame to a transmitting MLDthrough a first link.

The receiving MLD receives a probe response frame from the transmittingMLD through the first link.

The transmitting MLD includes a first transmitting STA operating in thefirst link and a second transmitting STA operating in a second link. Thereceiving MLD includes a first receiving STA operating in the first linkand a second receiving STA operating in the second link.

The probe request frame includes a profile field of the second receivingSTA. The profile field of the second receiving STA includes a firstcomplete information profile subfield.

When the first receiving STA requests partial information on the secondlink, a value of the first complete information profile subfield is setto 0. When the first receiving STA requests complete information on thesecond link, the value of the first complete information profilesubfield is set to 1.

That is, the probe response frame may be configured based on the valueof the first complete information profile subfield. When the value ofthe first complete information profile subfield is 0, the transmittingMLD may transfer the probe response frame including the partialinformation the second link. When the value of the first completeinformation profile subfield is 1, the transmitting MLD may transfer theprobe response frame including the complete information on the secondlink.

According to an embodiment proposed in the present specification,whether a non-AP STA requests complete information on other APs in an APMLD or requests partial information thereof may be identified through acomplete information profile subfield. Therefore, there is an advantagein that the AP MLD effectively determines whether a probe response frameincludes the complete information on other APs or includes the partialinformation thereof, by decoding the complete information profilesubfield.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a transmitting apparatus and/or receivingapparatus of the present specification.

FIG. 2 is a conceptual view illustrating the structure of a wirelesslocal area network (WLAN).

FIG. 3 illustrates a general link setup process.

FIG. 4 illustrates an example of a PPDU used in an IEEE standard.

FIG. 5 illustrates an operation based on UL-MU.

FIG. 6 illustrates an example of a trigger frame.

FIG. 7 illustrates an example of a common information field of a triggerframe.

FIG. 8 illustrates an example of a subfield included in a per userinformation field.

FIG. 9 describes a technical feature of the UORA scheme.

FIG. 10 illustrates an example of a PPDU used in the presentspecification.

FIG. 11 illustrates an example of a modified transmitting device and/orreceiving device of the present specification.

FIG. 12 illustrates an example of a structure of a non-AP MLD.

FIG. 13 illustrates an example in which an AP MLD and a non-AP MLD areconnected through a link setup procedure.

FIG. 14 illustrates an example in which a link is switched orreconnected.

FIG. 15 illustrates an example in which a link is switched orreconnected in detail.

FIG. 16 illustrates an operation of an AP MLD and non-AP MLD for linkswitching or reconnection.

FIG. 17 illustrates an operation of an AP MLD and non-AP MLD for linkswitching or reconnection.

FIG. 18 illustrates an operation of an AP MLD and non-AP MLD for linkswitching or reconnection.

FIG. 19 illustrates an operation of an AP MLD and non-AP MLD for linkswitching or reconnection.

FIG. 20 illustrates an operation of a non-AP MLD for requestinginformation on other APs.

FIG. 21 illustrates an example of an STA ratio per link in detail.

FIG. 22 illustrates an operation of an AP MLD and non-AP MLD for linkswitching or reconnection.

FIG. 23 illustrates an operation of an AP MLD and non-AP MLD for linkswitching or reconnection.

FIG. 24 illustrates an operation of an AP MLD and non-AP MLD for linkswitching or reconnection.

FIG. 25 illustrates an example of a multi-link element added in a proberequest.

FIG. 26 illustrates an example of using a link range field in amulti-link element.

FIG. 27 illustrates an example of a field newly proposed to indicatelink switching and reconnection.

FIG. 28 illustrates an example of a request IE format.

FIG. 29 illustrates an example of an extended request IE format.

FIG. 30 illustrates an example of a PV1 probe response option elementformat.

FIG. 31 illustrates an example of an MLD request element.

FIG. 32 illustrates another example of an MLD request element.

FIG. 33 illustrates an example in which a new element is defined basedon an MLD request element.

FIG. 34 illustrates another example of an MLD request element.

FIG. 35 illustrates another example of an MLD request element.

FIG. 36 illustrates another example of an MLD request element.

FIG. 37 illustrates another example of an MLD request element.

FIG. 38 illustrates an example of a field for requesting commoninformation.

FIG. 39 illustrates an example of an ML IE format defined in 802.11be.

FIG. 40 illustrates an example of a multi-link element format andmulti-link control field format.

FIG. 41 illustrates an example of a multi-link control field format.

FIG. 42 illustrates an example of an ML IE format.

FIG. 43 illustrates another example of an ML IE format.

FIG. 44 illustrates another example of an ML IE format.

FIG. 45 illustrates another example of an ML IE format.

FIG. 46 illustrates an example of a probe request frame including an MLIE format.

FIG. 47 illustrates another example of a probe request frame includingan ML IE format.

FIG. 48 illustrates another example of a probe request frame includingan ML IE format.

FIG. 49 illustrates another example of a probe request frame includingan ML IE format.

FIG. 50 illustrates an example of a multi-link control field format.

FIG. 51 illustrates an example in which a critical update request fieldis included in an ML IE format.

FIG. 52 illustrates an example of an MLD probe request which uses achange sequence element when critical update information is requested.

FIG. 53 illustrates another example of an MLD probe request which uses achange sequence element when critical update information is requested.

FIG. 54 illustrates an example in which a critical update request fieldis included in an ML IE format.

FIG. 55 illustrates an example in which a change sequence element isincluded in an ML IE format.

FIG. 56 illustrates an example of an MLD change sequence format.

FIG. 57 illustrates another example of an MLD change sequence format.

FIG. 58 illustrates an example of an MLD change sequence element.

FIG. 59 illustrates an example of a change sequence element in theconventional standard.

FIG. 60 illustrates another example in which a change sequence elementis included in an ML IE format.

FIG. 61 illustrates an example of a probe request frame for a criticalupdate information request.

FIG. 62 illustrates another example of a probe request frame for acritical update information request.

FIG. 63 illustrates another example of a probe request frame for acritical update information request.

FIG. 64 illustrates another example of a probe request frame for acritical update information request.

FIG. 65 is a flowchart illustrating a procedure in which a transmittingMLD provides a receiving MLD with complete or partial information on anAP, based on a probe response frame according to the present disclosure.

FIG. 66 is a flowchart illustrating a procedure in which a receiving MLDprovides a transmitting MLD with complete or partial information on anAP, based on a probe request frame according to the present disclosure.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

In the present specification, “A or B” may mean “only A”, “only B” or“both A and B”. In other words, in the present specification, “A or B”may be interpreted as “A and/or B”. For example, in the presentspecification, “A, B, or C” may mean “only A”, “only B”, “only C”, or“any combination of A, B, C”.

A slash (/) or comma used in the present specification may mean“and/or”. For example, “A/B” may mean “A and/or B”. Accordingly, “A/B”may mean “only A”, “only B”, or “both A and B”. For example, “A, B, C”may mean “A, B, or C”.

In the present specification, “at least one of A and B” may mean “onlyA”, “only B”, or “both A and B”. In addition, in the presentspecification, the expression “at least one of A or B” or “at least oneof A and/or B” may be interpreted as “at least one of A and B”.

In addition, in the present specification, “at least one of A, B, and C”may mean “only A”, “only B”, “only C”, or “any combination of A, B, andC”. In addition, “at least one of A, B, or C” or “at least one of A, B,and/or C” may mean “at least one of A, B, and C”.

In addition, a parenthesis used in the present specification may mean“for example”. Specifically, when indicated as “control information(EHT-signal)”, it may mean that “EHT-signal” is proposed as an exampleof the “control information”. In other words, the “control information”of the present specification is not limited to “EHT-signal”, and“EHT-signal” may be proposed as an example of the “control information”.In addition, when indicated as “control information (i.e., EHT-signal)”,it may also mean that “EHT-signal” is proposed as an example of the“control information”.

Technical features described individually in one figure in the presentspecification may be individually implemented, or may be simultaneouslyimplemented.

The following example of the present specification may be applied tovarious wireless communication systems. For example, the followingexample of the present specification may be applied to a wireless localarea network (WLAN) system. For example, the present specification maybe applied to the IEEE 802.11a/g/n/ac standard or the IEEE 802.11axstandard. In addition, the present specification may also be applied tothe newly proposed EHT standard or IEEE 802.11be standard. In addition,the example of the present specification may also be applied to a newWLAN standard enhanced from the EHT standard or the IEEE 802.11bestandard. In addition, the example of the present specification may beapplied to a mobile communication system. For example, it may be appliedto a mobile communication system based on long term evolution (LTE)depending on a 3rd generation partnership project (3GPP) standard andbased on evolution of the LTE. In addition, the example of the presentspecification may be applied to a communication system of a 5G NRstandard based on the 3GPP standard.

Hereinafter, in order to describe a technical feature of the presentspecification, a technical feature applicable to the presentspecification will be described.

FIG. 1 shows an example of a transmitting apparatus and/or receivingapparatus of the present specification.

In the example of FIG. 1 , various technical features described belowmay be performed. FIG. 1 relates to at least one station (STA). Forexample, STAs 110 and 120 of the present specification may also becalled in various terms such as a mobile terminal, a wireless device, awireless transmit/receive unit (WTRU), a user equipment (UE), a mobilestation (MS), a mobile subscriber unit, or simply a user. The STAs 110and 120 of the present specification may also be called in various termssuch as a network, a base station, a node-B, an access point (AP), arepeater, a router, a relay, or the like. The STAs 110 and 120 of thepresent specification may also be referred to as various names such as areceiving apparatus, a transmitting apparatus, a receiving STA, atransmitting STA, a receiving device, a transmitting device, or thelike.

For example, the STAs 110 and 120 may serve as an AP or a non-AP. Thatis, the STAs 110 and 120 of the present specification may serve as theAP and/or the non-AP.

STAs 110 and 120 of the present specification may support variouscommunication standards together in addition to the IEEE 802.11standard. For example, a communication standard (e.g., LTE, LTE-A, 5G NRstandard) or the like based on the 3GPP standard may be supported. Inaddition, the STA of the present specification may be implemented asvarious devices such as a mobile phone, a vehicle, a personal computer,or the like. In addition, the STA of the present specification maysupport communication for various communication services such as voicecalls, video calls, data communication, and self-driving(autonomous-driving), or the like.

The STAs 110 and 120 of the present specification may include a mediumaccess control (MAC) conforming to the IEEE 802.11 standard and aphysical layer interface for a radio medium.

The STAs 110 and 120 will be described below with reference to asub-figure (a) of FIG. 1 .

The first STA 110 may include a processor 111, a memory 112, and atransceiver 113. The illustrated process, memory, and transceiver may beimplemented individually as separate chips, or at least twoblocks/functions may be implemented through a single chip.

The transceiver 113 of the first STA performs a signaltransmission/reception operation. Specifically, an IEEE 802.11 packet(e.g., IEEE 802.11a/b/g/n/ac/ax/be, etc.) may be transmitted/received.

For example, the first STA 110 may perform an operation intended by anAP. For example, the processor 111 of the AP may receive a signalthrough the transceiver 113, process a reception (RX) signal, generate atransmission (TX) signal, and provide control for signal transmission.The memory 112 of the AP may store a signal (e.g., RX signal) receivedthrough the transceiver 113, and may store a signal (e.g., TX signal) tobe transmitted through the transceiver.

For example, the second STA 120 may perform an operation intended by anon-AP STA. For example, a transceiver 123 of a non-AP performs a signaltransmission/reception operation. Specifically, an IEEE 802.11 packet(e.g., IEEE 802.11a/b/g/n/ac/ax/be packet, etc.) may betransmitted/received.

For example, a processor 121 of the non-AP STA may receive a signalthrough the transceiver 123, process an RX signal, generate a TX signal,and provide control for signal transmission. A memory 122 of the non-APSTA may store a signal (e.g., RX signal) received through thetransceiver 123, and may store a signal (e.g., TX signal) to betransmitted through the transceiver.

For example, an operation of a device indicated as an AP in thespecification described below may be performed in the first STA 110 orthe second STA 120. For example, if the first STA 110 is the AP, theoperation of the device indicated as the AP may be controlled by theprocessor 111 of the first STA 110, and a related signal may betransmitted or received through the transceiver 113 controlled by theprocessor 111 of the first STA 110. In addition, control informationrelated to the operation of the AP or a TX/RX signal of the AP may bestored in the memory 112 of the first STA 110. In addition, if thesecond STA 120 is the AP, the operation of the device indicated as theAP may be controlled by the processor 121 of the second STA 120, and arelated signal may be transmitted or received through the transceiver123 controlled by the processor 121 of the second STA 120. In addition,control information related to the operation of the AP or a TX/RX signalof the AP may be stored in the memory 122 of the second STA 120.

For example, in the specification described below, an operation of adevice indicated as a non-AP (or user-STA) may be performed in the firstSTA 110 or the second STA 120. For example, if the second STA 120 is thenon-AP, the operation of the device indicated as the non-AP may becontrolled by the processor 121 of the second STA 120, and a relatedsignal may be transmitted or received through the transceiver 123controlled by the processor 121 of the second STA 120. In addition,control information related to the operation of the non-AP or a TX/RXsignal of the non-AP may be stored in the memory 122 of the second STA120. For example, if the first STA 110 is the non-AP, the operation ofthe device indicated as the non-AP may be controlled by the processor111 of the first STA 110, and a related signal may be transmitted orreceived through the transceiver 113 controlled by the processor 111 ofthe first STA 110. In addition, control information related to theoperation of the non-AP or a TX/RX signal of the non-AP may be stored inthe memory 112 of the first STA 110.

In the specification described below, a device called a(transmitting/receiving) STA, a first STA, a second STA, a STA1, a STA2,an AP, a first AP, a second AP, an AP1, an AP2, a(transmitting/receiving) terminal, a (transmitting/receiving) device, a(transmitting/receiving) apparatus, a network, or the like may imply theSTAs 110 and 120 of FIG. 1 . For example, a device indicated as, withouta specific reference numeral, the (transmitting/receiving) STA, thefirst STA, the second STA, the STA1, the STA2, the AP, the first AP, thesecond AP, the AP1, the AP2, the (transmitting/receiving) terminal, the(transmitting/receiving) device, the (transmitting/receiving) apparatus,the network, or the like may imply the STAs 110 and 120 of FIG. 1 . Forexample, in the following example, an operation in which various STAstransmit/receive a signal (e.g., a PPDU) may be performed in thetransceivers 113 and 123 of FIG. 1 . In addition, in the followingexample, an operation in which various STAs generate a TX/RX signal orperform data processing and computation in advance for the TX/RX signalmay be performed in the processors 111 and 121 of FIG. 1 . For example,an example of an operation for generating the TX/RX signal or performingthe data processing and computation in advance may include: 1) anoperation ofdetermining/obtaining/configuring/computing/decoding/encoding bitinformation of a sub-field (SIG, STF, LTF, Data) included in a PPDU; 2)an operation of determining/configuring/obtaining a time resource orfrequency resource (e.g., a subcarrier resource) or the like used forthe sub-field (SIG, STF, LTF, Data) included the PPDU; 3) an operationof determining/configuring/obtaining a specific sequence (e.g., a pilotsequence, an STF/LTF sequence, an extra sequence applied to SIG) or thelike used for the sub-field (SIG, STF, LTF, Data) field included in thePPDU; 4) a power control operation and/or power saving operation appliedfor the STA; and 5) an operation related todetermining/obtaining/configuring/decoding/encoding or the like of anACK signal. In addition, in the following example, a variety ofinformation used by various STAs fordetermining/obtaining/configuring/computing/decoding/decoding a TX/RXsignal (e.g., information related to a field/subfield/controlfield/parameter/power or the like) may be stored in the memories 112 and122 of FIG. 1 .

The aforementioned device/STA of the sub-figure (a) of FIG. 1 may bemodified as shown in the sub-figure (b) of FIG. 1 . Hereinafter, theSTAs 110 and 120 of the present specification will be described based onthe sub-figure (b) of FIG. 1 .

For example, the transceivers 113 and 123 illustrated in the sub-figure(b) of FIG. 1 may perform the same function as the aforementionedtransceiver illustrated in the sub-figure (a) of FIG. 1 . For example,processing chips 114 and 124 illustrated in the sub-figure (b) of FIG. 1may include the processors 111 and 121 and the memories 112 and 122. Theprocessors 111 and 121 and memories 112 and 122 illustrated in thesub-figure (b) of FIG. 1 may perform the same function as theaforementioned processors 111 and 121 and memories 112 and 122illustrated in the sub-figure (a) of FIG. 1 .

A mobile terminal, a wireless device, a wireless transmit/receive unit(WTRU), a user equipment (UE), a mobile station (MS), a mobilesubscriber unit, a user, a user STA, a network, a base station, aNode-B, an access point (AP), a repeater, a router, a relay, a receivingunit, a transmitting unit, a receiving STA, a transmitting STA, areceiving device, a transmitting device, a receiving apparatus, and/or atransmitting apparatus, which are described below, may imply the STAs110 and 120 illustrated in the sub-figure (a)/(b) of FIG. 1 , or mayimply the processing chips 114 and 124 illustrated in the sub-figure (b)of FIG. 1 . That is, a technical feature of the present specificationmay be performed in the STAs 110 and 120 illustrated in the sub-figure(a)/(b) of FIG. 1 , or may be performed only in the processing chips 114and 124 illustrated in the sub-figure (b) of FIG. 1 . For example, atechnical feature in which the transmitting STA transmits a controlsignal may be understood as a technical feature in which a controlsignal generated in the processors 111 and 121 illustrated in thesub-figure (a)/(b) of FIG. 1 is transmitted through the transceivers 113and 123 illustrated in the sub-figure (a)/(b) of FIG. 1 . Alternatively,the technical feature in which the transmitting STA transmits thecontrol signal may be understood as a technical feature in which thecontrol signal to be transferred to the transceivers 113 and 123 isgenerated in the processing chips 114 and 124 illustrated in thesub-figure (b) of FIG. 1 .

For example, a technical feature in which the receiving STA receives thecontrol signal may be understood as a technical feature in which thecontrol signal is received by means of the transceivers 113 and 123illustrated in the sub-figure (a) of FIG. 1 . Alternatively, thetechnical feature in which the receiving STA receives the control signalmay be understood as the technical feature in which the control signalreceived in the transceivers 113 and 123 illustrated in the sub-figure(a) of FIG. 1 is obtained by the processors 111 and 121 illustrated inthe sub-figure (a) of FIG. 1 . Alternatively, the technical feature inwhich the receiving STA receives the control signal may be understood asthe technical feature in which the control signal received in thetransceivers 113 and 123 illustrated in the sub-figure (b) of FIG. 1 isobtained by the processing chips 114 and 124 illustrated in thesub-figure (b) of FIG. 1 .

Referring to the sub-figure (b) of FIG. 1 , software codes 115 and 125may be included in the memories 112 and 122. The software codes 115 and126 may include instructions for controlling an operation of theprocessors 111 and 121. The software codes 115 and 125 may be includedas various programming languages.

The processors 111 and 121 or processing chips 114 and 124 of FIG. 1 mayinclude an application-specific integrated circuit (ASIC), otherchipsets, a logic circuit and/or a data processing device. The processormay be an application processor (AP). For example, the processors 111and 121 or processing chips 114 and 124 of FIG. 1 may include at leastone of a digital signal processor (DSP), a central processing unit(CPU), a graphics processing unit (GPU), and a modulator and demodulator(modem). For example, the processors 111 and 121 or processing chips 114and 124 of FIG. 1 may be SNAPDRAGON™ series of processors made byQualcomm®, EXYNOS™ series of processors made by Samsung®, A series ofprocessors made by Apple®, HELIO™ series of processors made byMediaTek®, ATOM™ series of processors made by Intel® or processorsenhanced from these processors.

In the present specification, an uplink may imply a link forcommunication from a non-AP STA to an SP STA, and an uplinkPPDU/packet/signal or the like may be transmitted through the uplink. Inaddition, in the present specification, a downlink may imply a link forcommunication from the AP STA to the non-AP STA, and a downlinkPPDU/packet/signal or the like may be transmitted through the downlink.

FIG. 2 is a conceptual view illustrating the structure of a wirelesslocal area network (WLAN).

An upper part of FIG. 2 illustrates the structure of an infrastructurebasic service set (BSS) of institute of electrical and electronicengineers (i.e. EE) 802.11.

Referring the upper part of FIG. 2 , the wireless LAN system may includeone or more infrastructure BSSs 200 and 205 (hereinafter, referred to asBSS). The BSSs 200 and 205 as a set of an AP and a STA such as an accesspoint (AP) 225 and a station (STA1) 200-1 which are successfullysynchronized to communicate with each other are not concepts indicatinga specific region. The BSS 205 may include one or more STAs 205-1 and205-2 which may be joined to one AP 230.

The BSS may include at least one STA, APs providing a distributionservice, and a distribution system (DS) 210 connecting multiple APs.

The distribution system 210 may implement an extended service set (ESS)240 extended by connecting the multiple BSSs 200 and 205. The ESS 240may be used as a term indicating one network configured by connectingone or more APs 225 or 230 through the distribution system 210. The APincluded in one ESS 240 may have the same service set identification(SSID).

A portal 220 may serve as a bridge which connects the wireless LANnetwork (i.e. EE 802.11) and another network (e.g., 802.X).

In the BSS illustrated in the upper part of FIG. 2 , a network betweenthe APs 225 and 230 and a network between the APs 225 and 230 and theSTAs 200-1, 205-1, and 205-2 may be implemented. However, the network isconfigured even between the STAs without the APs 225 and 230 to performcommunication. A network in which the communication is performed byconfiguring the network even between the STAs without the APs 225 and230 is defined as an Ad-Hoc network or an independent basic service set(IBSS).

A lower part of FIG. 2 illustrates a conceptual view illustrating theIBSS.

Referring to the lower part of FIG. 2 , the IBSS is a BSS that operatesin an Ad-Hoc mode. Since the IBSS does not include the access point(AP), a centralized management entity that performs a managementfunction at the center does not exist. That is, in the IBSS, STAs 250-1,250-2, 250-3, 255-4, and 255-5 are managed by a distributed manner. Inthe IBSS, all STAs 250-1, 250-2, 250-3, 255-4, and 255-5 may beconstituted by movable STAs and are not permitted to access the DS toconstitute a self-contained network.

FIG. 3 illustrates a general link setup process.

In S310, a STA may perform a network discovery operation. The networkdiscovery operation may include a scanning operation of the STA. Thatis, to access a network, the STA needs to discover a participatingnetwork. The STA needs to identify a compatible network beforeparticipating in a wireless network, and a process of identifying anetwork present in a particular area is referred to as scanning.Scanning methods include active scanning and passive scanning.

FIG. 3 illustrates a network discovery operation including an activescanning process. In active scanning, a STA performing scanningtransmits a probe request frame and waits for a response to the proberequest frame in order to identify which AP is present around whilemoving to channels. A responder transmits a probe response frame as aresponse to the probe request frame to the STA having transmitted theprobe request frame. Here, the responder may be a STA that transmits thelast beacon frame in a BSS of a channel being scanned. In the BSS, sincean AP transmits a beacon frame, the AP is the responder. In an IBSS,since STAs in the IBSS transmit a beacon frame in turns, the responderis not fixed. For example, when the STA transmits a probe request framevia channel 1 and receives a probe response frame via channel 1, the STAmay store BSS-related information included in the received proberesponse frame, may move to the next channel (e.g., channel 2), and mayperform scanning (e.g., transmits a probe request and receives a proberesponse via channel 2) by the same method.

Although not shown in FIG. 3 , scanning may be performed by a passivescanning method. In passive scanning, a STA performing scanning may waitfor a beacon frame while moving to channels. A beacon frame is one ofmanagement frames in IEEE 802.11 and is periodically transmitted toindicate the presence of a wireless network and to enable the STAperforming scanning to find the wireless network and to participate inthe wireless network. In a BSS, an AP serves to periodically transmit abeacon frame. In an IBSS, STAs in the IBSS transmit a beacon frame inturns. Upon receiving the beacon frame, the STA performing scanningstores information about a BSS included in the beacon frame and recordsbeacon frame information in each channel while moving to anotherchannel. The STA having received the beacon frame may store BSS-relatedinformation included in the received beacon frame, may move to the nextchannel, and may perform scanning in the next channel by the samemethod.

After discovering the network, the STA may perform an authenticationprocess in S320. The authentication process may be referred to as afirst authentication process to be clearly distinguished from thefollowing security setup operation in S340. The authentication processin S320 may include a process in which the STA transmits anauthentication request frame to the AP and the AP transmits anauthentication response frame to the STA in response. The authenticationframes used for an authentication request/response are managementframes.

The authentication frames may include information about anauthentication algorithm number, an authentication transaction sequencenumber, a status code, a challenge text, a robust security network(RSN), and a finite cyclic group.

The STA may transmit the authentication request frame to the AP. The APmay determine whether to allow the authentication of the STA based onthe information included in the received authentication request frame.The AP may provide the authentication processing result to the STA viathe authentication response frame.

When the STA is successfully authenticated, the STA may perform anassociation process in S330. The association process includes a processin which the STA transmits an association request frame to the AP andthe AP transmits an association response frame to the STA in response.The association request frame may include, for example, informationabout various capabilities, a beacon listen interval, a service setidentifier (SSID), a supported rate, a supported channel, RSN, amobility domain, a supported operating class, a traffic indication map(TIM) broadcast request, and an interworking service capability. Theassociation response frame may include, for example, information aboutvarious capabilities, a status code, an association ID (AID), asupported rate, an enhanced distributed channel access (EDCA) parameterset, a received channel power indicator (RCPI), a receivedsignal-to-noise indicator (RSNI), a mobility domain, a timeout interval(association comeback time), an overlapping BSS scanning parameter, aTIM broadcast response, and a QoS map.

In S340, the STA may perform a security setup process. The securitysetup process in S340 may include a process of setting up a private keythrough four-way handshaking, for example, through an extensibleauthentication protocol over LAN (EAPOL) frame.

FIG. 4 illustrates an example of a PPDU used in an IEEE standard.

As illustrated, various types of PHY protocol data units (PPDUs) areused in IEEE a/g/n/ac standards. Specifically, an LTF and a STF includea training signal, a SIG-A and a SIG-B include control information for areceiving STA, and a data field includes user data corresponding to aPSDU (MAC PDU/aggregated MAC PDU).

FIG. 4 also includes an example of an HE PPDU according to IEEE802.11ax. The HE PPDU according to FIG. 4 is an illustrative PPDU formultiple users. An HE-SIG-B may be included only in a PPDU for multipleusers, and an HE-SIG-B may be omitted in a PPDU for a single user.

As illustrated in FIG. 4 , the HE-PPDU for multiple users (MUs) mayinclude a legacy-short training field (L-STF), a legacy-long trainingfield (L-LTF), a legacy-signal (L-SIG), a high efficiency-signal A(HE-SIG A), a high efficiency-signal-B (HE-SIG B), a highefficiency-short training field (HE-STF), a high efficiency-longtraining field (HE-LTF), a data field (alternatively, an MAC payload),and a packet extension (PE) field. The respective fields may betransmitted for illustrated time periods (i.e., 4 or 8 μs).

Hereinafter, a resource unit (RU) used for a PPDU is described. An RUmay include a plurality of subcarriers (or tones). An RU may be used totransmit a signal to a plurality of STAs according to OFDMA. Further, anRU may also be defined to transmit a signal to one STA. An RU may beused for an STF, an LTF, a data field, or the like.

The RU described in the present specification may be used in uplink (UL)communication and downlink (DL) communication. For example, when UL-MUcommunication which is solicited by a trigger frame is performed, atransmitting STA (e.g., AP) may allocate a first RU (e.g.,26/52/106/242-RU, etc.) to a first STA through the trigger frame, andmay allocate a second RU (e.g., 26/52/106/242-RU, etc.) to a second STA.Thereafter, the first STA may transmit a first trigger-based PPDU basedon the first RU, and the second STA may transmit a second trigger-basedPPDU based on the second RU. The first/second trigger-based PPDU istransmitted to the AP at the same time period.

For example, when a DL MU PPDU is configured, the transmitting STA(e.g., AP) may allocate the first RU (e.g., 26/52/106/242-RU. etc.) tothe first STA, and may allocate the second RU (e.g., 26/52/106/242-RU,etc.) to the second STA. That is, the transmitting STA (e.g., AP) maytransmit HE-STF, HE-LTF, and Data fields for the first STA through thefirst RU in one MU PPDU, and may transmit HE-STF, HE-LTF, and Datafields for the second STA through the second RU.

FIG. 5 illustrates an operation based on UL-MU. As illustrated, atransmitting STA (e.g., AP) may perform channel access throughcontending (e.g., a backoff operation), and may transmit a trigger frame1030. That is, the transmitting STA may transmit a PPDU including thetrigger frame 1030. Upon receiving the PPDU including the trigger frame,a trigger-based (TB) PPDU is transmitted after a delay corresponding toSIFS.

TB PPDUs 1041 and 1042 may be transmitted at the same time period, andmay be transmitted from a plurality of STAs (e.g., user STAs) havingAIDs indicated in the trigger frame 1030. An ACK frame 1050 for the TBPPDU may be implemented in various forms.

A specific feature of the trigger frame is described with reference toFIG. 6 to FIG. 8 . Even if UL-MU communication is used, an orthogonalfrequency division multiple access (OFDMA) scheme or a MU MIMO schememay be used, and the OFDMA and MU-MIMO schemes may be simultaneouslyused.

FIG. 6 illustrates an example of a trigger frame. The trigger frame ofFIG. 6 allocates a resource for uplink multiple-user (MU) transmission,and may be transmitted, for example, from an AP. The trigger frame maybe configured of a MAC frame, and may be included in a PPDU.

Each field shown in FIG. 6 may be partially omitted, and another fieldmay be added. In addition, a length of each field may be changed to bedifferent from that shown in the figure.

A frame control field 1110 of FIG. 6 may include information related toa MAC protocol version and extra additional control information. Aduration field 1120 may include time information for NAV configurationor information related to an identifier (e.g., AID) of an STA.

In addition, an RA field 1130 may include address information of areceiving STA of a corresponding trigger frame, and may be optionallyomitted. A TA field 1140 may include address information of an STA(e.g., AP) which transmits the corresponding trigger frame. A commoninformation field 1150 includes common control information applied tothe receiving STA which receives the corresponding trigger frame. Forexample, a field indicating a length of an L-SIG field of an uplink PPDUtransmitted in response to the corresponding trigger frame orinformation for controlling content of an SIG-A field (i.e., HE-SIG-Afield) of the uplink PPDU transmitted in response to the correspondingtrigger frame may be included. In addition, as common controlinformation, information related to a length of a CP of the uplink PPDUtransmitted in response to the corresponding trigger frame orinformation related to a length of an LTF field may be included.

In addition, per user information fields 1160 #1 to 1160 #Ncorresponding to the number of receiving STAs which receive the triggerframe of FIG. 6 are preferably included. The per user information fieldmay also be called an “allocation field”.

In addition, the trigger frame of FIG. 6 may include a padding field1170 and a frame check sequence field 1180.

Each of the per user information fields 1160 #1 to 1160 #N shown in FIG.6 may include a plurality of subfields.

FIG. 7 illustrates an example of a common information field of a triggerframe. A subfield of FIG. 7 may be partially omitted, and an extrasubfield may be added. In addition, a length of each subfieldillustrated may be changed.

A length field 1210 illustrated has the same value as a length field ofan L-SIG field of an uplink PPDU transmitted in response to acorresponding trigger frame, and a length field of the L-SIG field ofthe uplink PPDU indicates a length of the uplink PPDU. As a result, thelength field 1210 of the trigger frame may be used to indicate thelength of the corresponding uplink PPDU.

In addition, a cascade identifier field 1220 indicates whether a cascadeoperation is performed. The cascade operation implies that downlink MUtransmission and uplink MU transmission are performed together in thesame TXOP. That is, it implies that downlink MU transmission isperformed and thereafter uplink MU transmission is performed after apre-set time (e.g., SIFS). During the cascade operation, only onetransmitting device (e.g., AP) may perform downlink communication, and aplurality of transmitting devices (e.g., non-APs) may perform uplinkcommunication.

A CS request field 1230 indicates whether a wireless medium state or anNAV or the like is necessarily considered in a situation where areceiving device which has received a corresponding trigger frametransmits a corresponding uplink PPDU.

An HE-SIG-A information field 1240 may include information forcontrolling content of an SIG-A field (i.e., HE-SIG-A field) of theuplink PPDU in response to the corresponding trigger frame.

A CP and LTF type field 1250 may include information related to a CPlength and LTF length of the uplink PPDU transmitted in response to thecorresponding trigger frame. A trigger type field 1260 may indicate apurpose of using the corresponding trigger frame, for example, typicaltriggering, triggering for beamforming, a request for block ACK/NACK, orthe like.

It may be assumed that the trigger type field 1260 of the trigger framein the present specification indicates a trigger frame of a basic typefor typical triggering. For example, the trigger frame of the basic typemay be referred to as a basic trigger frame.

FIG. 8 illustrates an example of a subfield included in a per userinformation field. A user information field 1300 of FIG. 8 may beunderstood as any one of the per user information fields 1160 #1 to 1160#N mentioned above with reference to FIG. 6 . A subfield included in theuser information field 1300 of FIG. 8 may be partially omitted, and anextra subfield may be added. In addition, a length of each subfieldillustrated may be changed.

A user identifier field 1310 of FIG. 8 indicates an identifier of an STA(i.e., receiving STA) corresponding to per user information. An exampleof the identifier may be the entirety or part of an associationidentifier (AID) value of the receiving STA.

In addition, an RU allocation field 1320 may be included. That is, whenthe receiving STA identified through the user identifier field 1310transmits a TB PPDU in response to the trigger frame, the TB PPDU istransmitted through an RU indicated by the RU allocation field 1320.

The subfield of FIG. 8 may include a coding type field 1330. The codingtype field 1330 may indicate a coding type of the TB PPDU. For example,when BCC coding is applied to the TB PPDU, the coding type field 1330may be set to ‘1’, and when LDPC coding is applied, the coding typefield 1330 may be set to ‘0’.

In addition, the subfield of FIG. 8 may include an MCS field 1340. TheMCS field 1340 may indicate an MCS scheme applied to the TB PPDU. Forexample, when BCC coding is applied to the TB PPDU, the coding typefield 1330 may be set to ‘1’, and when LDPC coding is applied, thecoding type field 1330 may be set to ‘0’.

Hereinafter, a UL OFDMA-based random access (UORA) scheme will bedescribed.

FIG. 9 describes a technical feature of the UORA scheme.

A transmitting STA (e.g., AP) may allocate six RU resources through atrigger frame as shown in FIG. 9 . Specifically, the AP may allocate a1^(st) RU resource (AID 0, RU 1), a 2^(nd) RU resource (AID 0, RU 2), a3^(rd) RU resource (AID 0, RU 3), a 4^(th) RU resource (AID 2045, RU 4),a 5^(th) RU resource (AID 2045, RU 5), and a 6^(th) RU resource (AID 3,RU 6). Information related to the AID 0, AID 3, or AID 2045 may beincluded, for example, in the user identifier field 1310 of FIG. 8 .Information related to the RU 1 to RU 6 may be included, for example, inthe RU allocation field 1320 of FIG. 8 . AID=0 may imply a UORA resourcefor an associated STA, and AID=2045 may imply a UORA resource for anun-associated STA. Accordingly, the 1^(st) to 3^(rd) RU resources ofFIG. 9 may be used as a UORA resource for the associated STA, the 4^(th)and 5^(th) RU resources of FIG. 9 may be used as a UORA resource for theun-associated STA, and the 6^(th) RU resource of FIG. 9 may be used as atypical resource for UL MU.

In the example of FIG. 9 , an OFDMA random access backoff (OBO) of anSTA1 is decreased to 0, and the STA1 randomly selects the 2^(nd) RUresource (AID 0, RU 2). In addition, since an OBO counter of an STA2/3is greater than 0, an uplink resource is not allocated to the STA2/3. Inaddition, regarding an STA4 in FIG. 9 , since an AID (e.g., AID=3) ofthe STA4 is included in a trigger frame, a resource of the RU 6 isallocated without backoff.

Specifically, since the STA1 of FIG. 9 is an associated STA, the totalnumber of eligible RA RUs for the STA1 is 3 (RU 1, RU 2, and RU 3), andthus the STA1 decreases an OBO counter by 3 so that the OBO counterbecomes 0. In addition, since the STA2 of FIG. 9 is an associated STA,the total number of eligible RA RUs for the STA2 is 3 (RU 1, RU 2, andRU 3), and thus the STA2 decreases the OBO counter by 3 but the OBOcounter is greater than 0. In addition, since the STA3 of FIG. 9 is anun-associated STA, the total number of eligible RA RUs for the STA3 is 2(RU 4, RU 5), and thus the STA3 decreases the OBO counter by 2 but theOBO counter is greater than 0.

Hereinafter, a PPDU transmitted/received in an STA of the presentspecification will be described.

FIG. 10 illustrates an example of a PPDU used in the presentspecification.

The PPDU of FIG. 10 may be called in various terms such as an EHT PPDU,a TX PPDU, an RX PPDU, a first type or N-th type PPDU, or the like. Forexample, in the present specification, the PPDU or the EHT PPDU may becalled in various terms such as a TX PPDU, a RX PPDU, a first type orN-th type PPDU, or the like. In addition, the EHT PPDU may be used in anEHT system and/or a new WLAN system enhanced from the EHT system.

The PPDU of FIG. 10 may indicate the entirety or part of a PPDU typeused in the EHT system. For example, the example of FIG. 10 may be usedfor both of a single-user (SU) mode and a multi-user (MU) mode. In otherwords, the PPDU of FIG. 10 may be a PPDU for one receiving STA or aplurality of receiving STAs. When the PPDU of FIG. 10 is used for atrigger-based (TB) mode, the EHT-SIG of FIG. 10 may be omitted. In otherwords, an STA which has received a trigger frame for uplink-MU (UL-MU)may transmit the PPDU in which the EHT-SIG is omitted in the example ofFIG. 10 .

In FIG. 10 , an L-STF to an EHT-LTF may be called a preamble or aphysical preamble, and may begenerated/transmitted/received/obtained/decoded in a physical layer.

A subcarrier spacing of the L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, andEHT-SIG fields of FIG. 10 may be determined as 312.5 kHz, and asubcarrier spacing of the EHT-STF, EHT-LTF, and Data fields may bedetermined as 78.125 kHz. That is, a tone index (or subcarrier index) ofthe L-STF, L-LTF, L-SIG, RL-SIG, U-SIG, and EHT-SIG fields may beexpressed in unit of 312.5 kHz, and a tone index (or subcarrier index)of the EHT-STF, EHT-LTF, and Data fields may be expressed in unit of78.125 kHz.

In the PPDU of FIG. 10 , the L-LTE and the L-STF may be the same asthose in the conventional fields.

The L-SIG field of FIG. 10 may include, for example, bit information of24 bits. For example, the 24-bit information may include a rate field of4 bits, a reserved bit of 1 bit, a length field of 12 bits, a parity bitof 1 bit, and a tail bit of 6 bits. For example, the length field of 12bits may include information related to a length or time duration of aPPDU. For example, the length field of 12 bits may be determined basedon a type of the PPDU. For example, when the PPDU is a non-HT, HT, VHTPPDU or an EHT PPDU, a value of the length field may be determined as amultiple of 3. For example, when the PPDU is an HE PPDU, the value ofthe length field may be determined as “a multiple of 3”+1 or “a multipleof 3”+2. In other words, for the non-HT, HT, VHT PPDI or the EHT PPDU,the value of the length field may be determined as a multiple of 3, andfor the HE PPDU, the value of the length field may be determined as “amultiple of 3”+1 or “a multiple of 3”+2.

For example, the transmitting STA may apply BCC encoding based on a 1/2coding rate to the 24-bit information of the L-SIG field. Thereafter,the transmitting STA may obtain a BCC coding bit of 48 bits. BPSKmodulation may be applied to the 48-bit coding bit, thereby generating48 BPSK symbols. The transmitting STA may map the 48 BPSK symbols topositions except for a pilot subcarrier{subcarrier index −21, −7, +7,+21} and a DC subcarrier{subcarrier index 0}. As a result, the 48 BPSKsymbols may be mapped to subcarrier indices −26 to −22, −20 to −8, −6 to−1, +1 to +6, +8 to +20, and +22 to +26. The transmitting STA mayadditionally map a signal of {−1, −1, −1, 1} to a subcarrier index {−28,−27, +27, +28}. The aforementioned signal may be used for channelestimation on a frequency domain corresponding to {−28, −27, +27, +28}.

The transmitting STA may generate an RL-SIG generated in the same manneras the L-SIG. BPSK modulation may be applied to the RL-SIG. Thereceiving STA may know that the RX PPDU is the HE PPDU or the EHT PPDU,based on the presence of the RL-SIG.

A universal SIG (U-SIG) may be inserted after the RL-SIG of FIG. 10 .The U-SIB may be called in various terms such as a first SIG field, afirst SIG, a first type SIG, a control signal, a control signal field, afirst (type) control signal, or the like.

The U-SIG may include information of N bits, and may include informationfor identifying a type of the EHT PPDU. For example, the U-SIG may beconfigured based on two symbols (e.g., two contiguous OFDM symbols).Each symbol (e.g., OFDM symbol) for the U-SIG may have a duration of 4us. Each symbol of the U-SIG may be used to transmit the 26-bitinformation. For example, each symbol of the U-SIG may betransmitted/received based on 52 data tomes and 4 pilot tones.

Through the U-SIG (or U-SIG field), for example, A-bit information(e.g., 52 un-coded bits) may be transmitted. A first symbol of the U-SIGmay transmit first X-bit information (e.g., 26 un-coded bits) of theA-bit information, and a second symbol of the U-SIB may transmit theremaining Y-bit information (e.g. 26 un-coded bits) of the A-bitinformation. For example, the transmitting STA may obtain 26 un-codedbits included in each U-SIG symbol. The transmitting STA may performconvolutional encoding (i.e., BCC encoding) based on a rate of R=1/2 togenerate 52-coded bits, and may perform interleaving on the 52-codedbits. The transmitting STA may perform BPSK modulation on theinterleaved 52-coded bits to generate 52 BPSK symbols to be allocated toeach U-SIG symbol. One U-SIG symbol may be transmitted based on 65 tones(subcarriers) from a subcarrier index −28 to a subcarrier index +28,except for a DC index 0. The 52 BPSK symbols generated by thetransmitting STA may be transmitted based on the remaining tones(subcarriers) except for pilot tones, i.e., tones −21, −7, +7, +21.

For example, the A-bit information (e.g., 52 un-coded bits) generated bythe U-SIG may include a CRC field (e.g., a field having a length of 4bits) and a tail field (e.g., a field having a length of 6 bits). TheCRC field and the tail field may be transmitted through the secondsymbol of the U-SIG. The CRC field may be generated based on 26 bitsallocated to the first symbol of the U-SIG and the remaining 16 bitsexcept for the CRC/tail fields in the second symbol, and may begenerated based on the conventional CRC calculation algorithm. Inaddition, the tail field may be used to terminate trellis of aconvolutional decoder, and may be set to, for example, “000000”.

The A-bit information (e.g., 52 un-coded bits) transmitted by the U-SIG(or U-SIG field) may be divided into version-independent bits andversion-dependent bits. For example, the version-independent bits mayhave a fixed or variable size. For example, the version-independent bitsmay be allocated only to the first symbol of the U-SIG, or theversion-independent bits may be allocated to both of the first andsecond symbols of the U-SIG. For example, the version-independent bitsand the version-dependent bits may be called in various terms such as afirst control bit, a second control bit, or the like.

For example, the version-independent bits of the U-SIG may include a PHYversion identifier of 3 bits. For example, the PHY version identifier of3 bits may include information related to a PHY version of a TX/RX PPDU.For example, a first value of the PHY version identifier of 3 bits mayindicate that the TX/RX PPDU is an EHT PPDU. In other words, when thetransmitting STA transmits the EHT PPDU, the PHY version identifier of 3bits may be set to a first value. In other words, the receiving STA maydetermine that the RX PPDU is the EHT PPDU, based on the PHY versionidentifier having the first value.

For example, the version-independent bits of the U-SIG may include aUL/DL flag field of 1 bit. A first value of the UL/DL flag field of 1bit relates to UL communication, and a second value of the UL/DL flagfield relates to DL communication.

For example, the version-independent bits of the U-SIG may includeinformation related to a TXOP length and information related to a BSScolor ID.

For example, when the EHT PPDU is divided into various types (e.g.,various types such as an EHT PPDU related to an SU mode, an EHT PPDUrelated to a MU mode, an EHT PPDU related to a TB mode, an EHT PPDUrelated to extended range transmission, or the like), informationrelated to the type of the EHT PPDU may be included in theversion-dependent bits of the U-SIG.

For example, the U-SIG may include: 1) a bandwidth field includinginformation related to a bandwidth; 2) a field including informationrelated to an MCS scheme applied to EHT-SIG; 3) an indication fieldincluding information regarding whether a dual subcarrier modulation(DCM) scheme is applied to EHT-SIG; 4) a field including informationrelated to the number of symbol used for EHT-SIG; 5) a field includinginformation regarding whether the EHT-SIG is generated across a fullband; 6) a field including information related to a type of EHT-LTF/STF;and 7) information related to a field indicating an EHT-LTF length and aCP length.

In the following example, a signal represented as a (TX/RX/UL/DL)signal, a (TX/RX/UL/DL) frame, a (TX/RX/UL/DL) packet, a (TX/RX/UL/DL)data unit, (TX/RX/UL/DL) data, or the like may be a signaltransmitted/received based on the PPDU of FIG. 10 . The PPDU of FIG. 10may be used to transmit/receive frames of various types. For example,the PPDU of FIG. 10 may be used for a control frame. An example of thecontrol frame may include a request to send (RTS), a clear to send(CTS), a power save-poll (PS-poll), BlockACKReq, BlockAck, a null datapacket (NDP) announcement, and a trigger frame. For example, the PPDU ofFIG. 10 may be used for a management frame. An example of the managementframe may include a beacon frame, a (re-)association request frame, a(re-)association response frame, a probe request frame, and a proberesponse frame. For example, the PPDU of FIG. 10 may be used for a dataframe. For example, the PPDU of FIG. 10 may be used to simultaneouslytransmit at least two or more of the control frame, the managementframe, and the data frame.

FIG. 11 illustrates an example of a modified transmitting device and/orreceiving device of the present specification.

Each device/STA of the sub-figure (a)/(b) of FIG. 1 may be modified asshown in FIG. 11 . A transceiver 630 of FIG. 11 may be identical to thetransceivers 113 and 123 of FIG. 1 . The transceiver 630 of FIG. 11 mayinclude a receiver and a transmitter.

A processor 610 of FIG. 11 may be identical to the processors 111 and121 of FIG. 1 . Alternatively, the processor 610 of FIG. 11 may beidentical to the processing chips 114 and 124 of FIG. 1 .

A memory 620 of FIG. 11 may be identical to the memories 112 and 122 ofFIG. 1 . Alternatively, the memory 620 of FIG. 11 may be a separateexternal memory different from the memories 112 and 122 of FIG. 1 .

Referring to FIG. 11 , a power management module 611 manages power forthe processor 610 and/or the transceiver 630. A battery 612 suppliespower to the power management module 611. A display 613 outputs a resultprocessed by the processor 610. A keypad 614 receives inputs to be usedby the processor 610. The keypad 614 may be displayed on the display613. A SIM card 615 may be an integrated circuit which is used tosecurely store an international mobile subscriber identity (IMSI) andits related key, which are used to identify and authenticate subscriberson mobile telephony devices such as mobile phones and computers.

Referring to FIG. 11 , a speaker 640 may output a result related to asound processed by the processor 610. A microphone 641 may receive aninput related to a sound to be used by the processor 610.

Hereinafter, a technical feature of a multi-link (ML) supported by anSTA of the present specification will be described.

The STA (AP and/or non-AP STA) of the present specification may supportML communication. The ML communication may imply communicationsupporting a plurality of links. A link related to the ML communicationmay include channels (e.g., 20/40/80/160/240/320 MHz channels) of 2.4GHz, 5 GHz, and 6 GHz bands.

The plurality of links used for the ML communication may be set upvariously. For example, the plurality of links supported in one STA forthe ML communication may be a plurality of channels in the 2.4 GHz band,a plurality of channels in the 5 GHz band, and a plurality of channelsin the 6 GHz band. Alternatively, the plurality of links supported inone STA for the ML communication may be a combination of at least onechannel in the 2.4 GHz band (or 5 GHz/6 GHz band) and at least onechannel in the 5 GHz band (or 2.4 GHz/6 GHz band). Meanwhile, at leastone of the plurality of links supported in one STA for the MLcommunication may be a channel to which preamble puncturing is applied.

The STA may perform ML setup to perform the ML communication. The MLsetup may be performed based on a control frame or a management framesuch as Beacon, Probe Request/Response, Association Request/Response, orthe like. For example, information on the ML setup may be included in anelement field included in the Beacon, the Probe Request/Response, andthe Association Request/Response.

Upon completion of the ML setup, an enabled link for the MLcommunication may be determined. The STA may perform frame exchangethrough at least one of the plurality of links determined as the enabledlink. For example, the enabled link may be used for at least one of themanagement frame, the control frame, and the data frame.

When one STA supports a plurality of links, a transmitting/receivingdevice supporting each link may operate as if it is one logical STA. Forexample, one STA supporting two links may be represented by one MLdevice (MLD) including a first STA for a first link and a second STA fora second link. For example, one AP supporting two links may berepresented by one AP MLD including a first AP for the first link and asecond AP for the second link. In addition, one non-AP supporting twolinks may be represented by one non-AP MLD including the first STA forthe first link and the second STA including the second link.

Hereinafter, a feature of the ML setup will be described morespecifically.

An MLD (AP MLD and/or non-AP MLD) may transmit information on a linksupportable by the MLD through the ML setup. The information on the linkmay be configured variously. For example, the information on the linkmay include at least one of: 1) information on whether the MLD (or STA)supports a simultaneous RX/TX operation; 2) information on thenumber/upper limit of uplink/downlink links supported by the MLD (orSTA); 3) information on a location/band/resource of the uplink/downlinklinks supported by the MLD (or STA); 4) information on a type(management, control, data, etc.) of a frame which is usable orpreferred in at least one uplink/downlink link; 5) information on an ACKpolicy which is usable or preferred in at least one uplink/downlinklink; and 6) information on a traffic identifier (TID) which is usableor preferred in at least one uplink/downlink link. The TID is related toa priority of traffic data, and is represented by 8 types of valuesaccording to the conventional WLAN standard. That is, 8 TID valuescorresponding to four access categories (ACs) (AC_BK(background),AC_BE(best effort), AC_VI(video), AC_VO(voice)) may be defined accordingto the conventional WLAN standard.

For example, it may be pre-set such that all TIDs are mapped to theuplink/downlink links. Specifically, when negotiation is not achievedthrough the ML setup, all TIDs are used for ML communication, and whenmapping between the uplink/downlink link and the TID is negotiatedthrough additional ML setup, the negotiated TID may be used for the MLcommunication.

A plurality of links related to the ML communication and usable by atransmitting MLD and a receiving MLD may be configured through the MLsetup, and such a link may be called an “enabled link”. The “enabledlink” may be called variously. For example, it may be called variouslysuch as a first link, a second link, a transmission link, a receptionlink, or the like.

After completion of the ML setup, the MLD may update the ML setup. Forexample, when there is a need to update information on the link, the MLDmay transmit information on a new link. The information on the new linkmay be transmitted based on at least one of a management frame, acontrol frame, and a data frame.

A device described hereinafter may be a device of FIG. 1 and/or FIG. 11, and a PPDU may be a PPDU of FIG. 10 . The device may be an AP or anon-AP STA. The device described hereinafter may be an AP multi-linkdevice (MLD) or non-AP STA MLD supporting a multi-link.

In an extremely high throughput (EHT) which is a standard discussedafter 802.11ax, a multi-link environment in which one or more bands areused simultaneously is taken into consideration. When a device supportsa multi-link, the device may simultaneously or alternately use one ormore bands (e.g., 2.4 GHz, 5 GHz, 6 GHz, 60 GHz, etc.).

In the specification described below, the MLD implies a multi-linkdevice. The MLD has one or more connected STAs, and has one MAC serviceaccess point (SAP) leading to an upper link layer (logical link control(LLC)). The MLD may imply a physical device or a logical device.Hereinafter, the device may imply the MLD.

In the specification described below, a transmitting device and areceiving device may imply the MLD. A first link of thereceiving/transmitting device may be a terminal (e.g., STA or AP) whichis included in the transmitting/receiving device and which performssignal transmission/reception through the first link. A second link ofthe receiving/transmitting device may be a terminal (e.g., STA or AP)which is included in the receiving/transmitting device and whichperforms signal transmission/reception through the second link.

Roughly, two types of multi-link operations may be supported inIEEE802.11be. For example, simultaneously transmit and receive (STR) andnon-STR operations may be considered. For example, the STR may bereferred to as an asynchronous multi-link operation, and the non-STR maybe referred to as a synchronous multi-link operation. The multi-link mayinclude a multi-band. That is, the multi-link may imply a link includedin several frequency bands, or may imply several links included in onefrequency band.

A multi-link technique is considered in EHT (11be). In this case, themulti-link may include a multi-band. That is, the multi-band mayrepresent a link of several bands, and also may represent severalmulti-links in one band. Roughly, two types of multi-link operations areconsidered. An asynchronous operation in which simultaneous TX/RX ispossible in several links and a synchronous operation in which thesimultaneous TX/RX is not possible are considered. Hereinafter, acapability which enables simultaneous reception and transmission inseveral links is called simultaneous transmit and receive (STR), and anSTA having the SRT capability is called an STR multi-link device (MLD),and an STA not having the STR capability is called a non-STR MLD.

In the specification described below, for convenience of explanation, itis described that the MLD (or a processor of the MLD) controls at leastone STA, but the present disclosure is not limited thereto. As describedabove, the at least one STA may also transmit/receive a signalindependently irrespective of the MLD.

According to an embodiment, an AP MLD or a non-AP MLD may be configuredwith a structure having a plurality of links. In other words, the non-APMLD may support a plurality of links. The non-AP MLD may include aplurality of STAs. Each of the plurality of STAs may have a link.

A multi-link device (MLD) structure in which one AP/non-AP MLD supportsseveral links is considered as a core technique in the EHT standard(802.11be standard). An STA included in the non-AP MLD may transferinformation on other STAs in the non-AP MLD together through one link.Accordingly, there is an advantage in that an overhead is reduced forframe exchange. In addition, there is an advantage in that link usageefficient of the STA is increased, and power consumption is decreased.

FIG. 12 illustrates an example of a structure of a non-AP MLD.

Referring to FIG. 12 , the non-AP MLD may be configured with a structurehaving a plurality of links. In other words, the non-AP MLD may supporta plurality of links. The non-AP MLD may include a plurality of STAs.Each of the plurality of STAs may have a link. Although FIG. 12illustrates the example of the structure of the non-AP MLD structure, astructure of an AP MLD may also be configured to be the same as theexample of the structure of the non-AP MLD illustrated in FIG. 12 .

For example, the non-AP MLD may include an STA 1, an STA 2, and an STA3. The STA 1 may operate in a link 1. The link 1 may be included in a 5GHz band. The STA 2 may operate in a link 2. The link 2 may be includedin a 6 GHz band. The STA 3 may operate in a link 3. The link 3 may beincluded in a 6 GHz band. A band in which the link 1/2/3 is included isfor exemplary purposes only, and may also be included in 2.4, 5, and 6GHz bands.

As such, in case of the AP/non-AP MLD supporting the multi-link, APs ofthe AP MLD and STAs of the non-AP MLD may be connected to respectivelinks through a link setup procedure. In addition, the link connected inthis case may be switched or re-connected to another link by the AP MLDor the non-AP MLD according to a situation.

In addition, in the EHT standard, the link may be classified into ananchored link and a non-anchored link to reduce power consumption. Theanchored link or the non-anchored link may be called variously. Forexample, the anchored link may be called a primary link. Thenon-anchored link may be called a secondary link.

According to an embodiment, the AP MLD supporting the multi-link maymanage each link by specifying the link as the anchored link or thenon-anchored link. The AP MLD may support one or more links as theanchored link, among a plurality of links. The non-AP MLD may use one ormore anchored links thereof selected from an anchored link list (ananchored link list supported by the AP MLD).

For example, the anchored link may be used for not only frame exchangefor synchronization but also non-data frame exchange (i.e., beacon andmanagement frames). In addition, the non-anchored link may be used onlyfor data frame exchange.

The non-AP MLD may monitor only the anchored link to receive beacon andmanagement frames during an idle period. Therefore, the non-AP MLD shallbe connected to at least one anchored link to receive the beacon andmanagement frames. The one or more anchored links shall always maintainan enable state. Unlike this, the non-anchored link is used only fordata frame exchange. Therefore, an STA corresponding to the non-anchoredlink (or an STA connected to the non-anchored link) may enter a dozestate during the idle period in which a channel/link is not used.Accordingly, there is an advantage in that power consumption can bedecreased.

Therefore, in the specification described below, a protocol in which anAP MLD or a non-AP MLD dynamically recommends or requests a linkreconnection according to a situation may be proposed for efficient linkconnection. In addition, in the specification described below, ananchored link reconnection protocol may be additionally proposed inconsideration of a characteristic of not only a typical link but also ananchored link used for the purpose of power reduction.

Embodiment for Link Switching and Reconnection

According to an embodiment, each link between an AP MLD and a non-AP MLDmay be determined in an association or (re)association procedure. Inthis case, the AP MLD and the non-AP MLD may perform frame exchangethrough a connected link. A specific embodiment in which the AP MLD andthe non-AP MLD are connected through a link setup procedure may bedescribed with reference to FIG. 13 .

FIG. 13 illustrates an example in which an AP MLD and a non-AP MLD areconnected through a link setup procedure.

Referring to FIG. 13 , the AP MLD may include an AP 1, an AP 2, and anAP 3. The non-AP MLD may include an STA 1 and an STA 2. The AP 1 and theSTA 1 may be connected through a link 1. The AP 2 and the STA 2 may beconnected through a link 2.

For example, the AP 1 and the STA 1 may be connected through the link 1by using a first link setup procedure. The AP 2 and the STA 2 may beconnected through the link 2 by using a second link setup procedure. Asanother example, the AP MLD and the non-AP MLD may be connected by usingone link setup procedure. In other words, the AP MLD and the non-AP MLDmay be connected through the link 1 and the link 2, based on one linksetup procedure.

As described above, each of the AP and the STA may perform frameexchange through the connected link. In addition, information on otherAPs for different links or other STAs for different links may betransmitted/received through one link.

However, after the link setup procedure, the AP MLD or the non-AP MLDmay request link switching or reconnection for more efficient frameexchange (e.g., load balancing or interference avoiding, etc.) accordingto a situation/environment.

An embodiment for the link switching or reconnection may be describedwith reference to FIG. 14 .

FIG. 14 illustrates an example in which a link is switched orreconnected.

Referring to FIG. 14 , an STA 2 is previously connected to an AP 2.There may be an excessive data load of the AP 2 at a later time. The STA2 may be reconnected to an AP 3 which has a relatively small data load.In this case, there is an advantage in that an AP MLD and a non-AP MLDmay effectively perform data exchange.

FIG. 15 illustrates an example in which a link is switched orreconnected in detail.

Referring to FIG. 15 , an AP 1 of an AP MLD may be connected to an STA 1of a non-AP MLD through a link 1. An AP 2 of the AP MLD may be connectedto an STA 2 through a link 2. At a later time, the STA 2 mayattempt/request a connection to an AP 3 through link switching orreconnection, and the STA 2 may be connected to the AP 3 through thelink 2, based on the link switching or reconnection.

According to an embodiment, the non-AP MLD and the AP MLD may request alink transition for performance improvement. The AP MLD and the non-APMLD may transmit and receive/exchange a variety of information for eachcurrent link and information on a link state. Therefore, based on thelink state and the variety of information for each current link, the APMLD and the non-AP MLD may select a link which is more appropriate totransmit/receive a signal, and may transmit the aforementionedinformation to facilitate the selection. For example, the variety ofinformation for each current link may include information on a datatraffic load for each link and channel access capability between thelinks. For example, the link state may be set to ‘disable’ or ‘enable’or the like.

In the specification described below, a process in which the APMLD/non-AP MLD negotiates with the non-AP MLD/AP MLD to requestswitching or reconnection to another link, not a link connected toimprove performance, may be called “link switching negotiation”. Theterm of the “link switching negotiation” may be variously called andchangeable.

In the link switching negotiation process, the non-AP MLD (or AP MLD)may request to switch a link connected to a specific STA to anotherlink, and the AP MLD (or non-AP MLD) may respond to this request througha request accept or decline message.

For example, as shown in FIG. 15 , when the link switching is agreedthrough the link switching negotiation, the STA may perform a linkre-setup process in which the existing link is reconnected by switchingfrom the AP 2 to the AP 3.

Hereinafter, the link switching or reconnection process may be describeddistinctively for a case of being requested by the AP MLD and a case ofbeing requested by the non-AP MLD.

Embodiment in which an AP MLD Requests Link Switching or Reconnection

According to an embodiment, for effective data transmission, an AP MLDmay request a non-AP MLD for link switching or reconnection. Forexample, for load balancing, the AP MLD may request an STA for switchingor reconnection to a more effective link, based on data traffic of eachAP.

For example, the AP MLD may calculate/verify/confirm a link appropriatefor STAs of the non-AP MLD, based on data traffic load information foreach AP and/or channel access capability information between the links(e.g., information on simultaneous TX/RX (STR) capability, etc.), or thelike. Thereafter, the AP MLD may request the STA (or non-AP MLD) for thelink switching or reconnection, based on the data traffic load for eachAP and/or the channel access capability information between the links,or the like.

As described above, when the link switching is requested, the AP MLD maytransmit link information which is considered most appropriate for thenon-AP MLD through the request message. For example, the request messagemay include a beacon or management frame, or the like.

An element or field including link information which is considered mostappropriate may be proposed, in association with the embodimentdescribed above. The newly proposed element or field may be defined as a“recommended link”. The “recommended link” is for exemplary purposes,and the specific term “element” or “field” is changeable.

recommend link (element/field): an element or field used when an AP MLDrecommends a link which is most appropriate for an STA of a non-AP MLD,based on a variety of information for each link (e.g., a data load foreach link, etc.). For example, the recommended link (element/field) maybe indicated by AP MLD's link ID information or AP BSS information, etc.In other words, the recommended link (element/field) may include APMLD's link ID information or AP BSS information, etc.

According to an embodiment, the recommended link (element/field) may betransmitted optionally by being included in a link switching response.For example, the STA may establish a connection to a link recommended bythe AP, based on the element/field (i.e., recommended link). As anotherexample, the STA may request a connection to a link different from theindicated link, based on the element/field (i.e., recommended link) andadditional information owned by the STA.

A specific signal exchange process of the AP MLD and non-AP MLD may bedescribed with reference to FIG. 16 according to the aforementionedembodiment.

FIG. 16 illustrates an operation of an AP MLD and non-AP MLD for linkswitching or reconnection.

Referring to FIG. 16 , in a situation where an STA 2 is connected to anAP 2 through a link 2, a lot of data traffic may be concentrated in theAP 2. In other words, in the situation where the STA 2 is connected tothe AP 2 through the link 2, a lot of data traffic may be generated inthe AP 2.

The AP MLD (or AP 2) may request the non-AP MLD (or STA 2) to reconnectto an AP 3 which has relatively few STA connections. In general, amessage for requesting the reconnection is transmitted to the STA (i.e.,the STA 2) which desires to be reconnected, but may be transmitted toany STA (i.e., other STAs) according to a situation (e.g., a channelsituation or a link state). In other words, an STA to which a requestmessage (e.g., a link switching request frame) for requesting thereconnection is transmitted may be switched according to the channelsituation or the link state.

For example, the STA (i.e., STA 2) which has received the requestmessage for requesting the reconnection may transmit a response messageof “accept” (e.g., a link switching response frame) when the request isaccepted. As another example, the STA (i.e., STA 2) may transmit aresponse message of “decline” when the request is declined.

In general, the STA (e.g., STA 2) which accepts the reconnectiontransmits the response message to the existing link (e.g., a linkconnected before the reconnection), but the response message may also betransmitted through any link (i.e., other STAs) by using a multi-linkcharacteristic.

If the STA 2 accepts the link reconnection request, after transmissionof the response message, the STA 2 may disconnect from the existing AP 2and may request a link reconnection to an AP 3. In this case, areconnection request process may be performed identically to a linksetup process between the existing MLDs. After the link setup process iscomplete between the AP 3 and the STA 2, the STA 2 may perform frameexchange with the AP 3 through the link 2.

Otherwise, if the STA 2 declines the link reconnection request, the STA2 and the AP 2 may directly use the previously connected link (i.e.,link 2).

According to an embodiment, when the AP requests the STA for linkswitching, if an appropriate link is recommended, the STA may switch thelink to the recommended link or may not switch the link. For example, inorder for the AP to recommend the link appropriate for the STA, theaforementioned recommended link may be used.

For example, the STA may accept the link switching with a responsemessage for the request message for requesting the reconnection of theAP. The STA may accept/verify the link switching to the recommendedlink, and may request the AP for another link switching, based ondifferent information other than information included in the requestmessage.

Accordingly, the AP may need to notify the STA of whether the responsemessage is accepted. To this end, the AP may transmit to the STA aconfirmation message (e.g., a link switching confirmation frame) for aresponse message (e.g., a link switching response frame) of the STA.

A specific operation of the AP MLD and non-AP MLD of the aforementionedembodiment may be described with reference to FIG. 17 .

FIG. 17 illustrates an operation of an AP MLD and non-AP MLD for linkswitching or reconnection.

Referring to FIG. 17 , an AP 2 may request an STA 2 for link switchingby including recommended link information. In other words, the AP 2 maytransmit to the STA 2 a link switching request frame including therecommended link information.

The STA 2 may transmit whether a link request is accepted through a linkswitching response frame.

For example, when link switching is accepted, the STA 2 may transmit alink switching response frame including information on a link to beswitched. In this case, the information on the link to be switched maybe identical to, or different from, a recommended link.

As another example, when the STA 2 responds with a link switchingresponse frame by selecting a different link other than the recommendedlink provided by the AP 2, the AP may transmit to the STA a messageindicating whether it is finally accepted. The message may be called alink switching confirmation frame.

For example, the AP 2 may accept link switching to a link specified bythe STA 2, through the link switching confirmation frame. The STA 2 mayattempt to switch the link to the link specified by the STA 2, based onthe link switching confirmation frame.

As another example, the AP 2 may decline the link switching to the linkspecified by the STA 2, through the link switching confirmation frame.The STA 2 and the AP 2 may maintain a connection with the previouslyconnected link without having to switch the link.

The embodiment illustrated in FIG. 17 may also apply to a case where theAP transmits the link switching request frame without including therecommended link information. For example, when the AP (e.g., AP 2)transmits the link switching request frame to the STA (e.g., STA 2)without the recommended link information, the STA may directly specify alink to be switched, based on information owned by the STA, and then mayrespond to the AP through the link switching response frame. In thiscase, the AP shall also finally transmit the link switching confirmationframe for the accept. Therefore, even if the recommend link informationis not included in the link switching request frame, the embodiment inwhich the AP transmits the link switching confirmation frame may apply.

Embodiment in which a Non-AP MLD Requests Link Switching or Reconnection

According to an embodiment, a non-AP MLD may request an AP MLD for linkswitching or reconnection in order to perform efficient datatransmission. For example, in order to use STR capability in datatransmission, the non-AP MLD may request the AP MLD to switch orreconnect to a connected link.

FIG. 18 illustrates an operation of an AP MLD and non-AP MLD for linkswitching or reconnection.

Referring to FIG. 18 , the AL MLD and the non-AP MLD may perform linkswitching negotiation. An STA 2 of the non-AP MLD may transmit a linkswitching request frame to an AP 2 of the AP MLD. The AP 2 of the AP MLDmay transmit a link switching response frame to the STA 2 of the non-APMLD, in response to the link switching request frame. The link switchingrequest frame or the link switching response frame may betransmitted/received through a link to be switched, but the presentdisclosure is not limited thereto. The link switching request frame orthe link switching response frame may be transmitted/received throughnot only the link to be switched but also various links.

The non-AP MLD may request the link switching or reconnection throughvarious methods. Hereinafter, three methods may be proposed as a methodin which the non-AP requests the link switching or reconnection.Specifically, the three methods may be described in the order of asolicited method, an unsolicited method, and a general method.

1) Solicited method: a method in which the non-AP MLD requests the APMLD for a variety of information for link (re)selection to receive thevariety of information. For example, the variety of information mayinclude information on capability, operation elements, and BSSparameters.

According to an embodiment, the method in which the STA requestsinformation on other APs of the connected AP MLD may be used not only acase where the link is reconfigured but also various cases. For example,after the multi-link setup, for the link switching, the STA may requestBSS parameter information on other APs, and may select a best link,based on the received information. Alternatively, in a discoveryprocess, the STA may request the AP MLD for BSS load information of eachAP, and may select a link for performing link setup, based on thereceived information (herein, it is assumed that the number of APS ofthe AP MLD is greater than the number of STAs of the non-AP MLD).

Accordingly, an AP which has received an information request message maytransmit any information such as capability information, BSS parameterinformation, critical parameters, and/or operation element informationor the like for all APs in the AP MLD. The aforementioned example mayapply to all embodiments described below.

2) Unsolicited method: a method in which the AP transmits a variety ofinformation for the link (re)selection, without an additionalinformation request. The STA may utilize the received information invarious situations. According to an embodiment, a method in which the APof the AP MLD transmits information on other APs, without an additionalinformation request of the STA, may be used not only in a case where thelink is reconfigured but also various cases. Accordingly, an AP whichhas received an information request message may transmit any informationsuch as capability information, BSS parameter information, criticalparameters, and/or operation element information or the like for all APsin the AP MLD. The aforementioned example may apply to all embodimentsdescribed below.

3) General method: a method in which the non-AP MLD requests a link(re)selection without additional information, based on informationobtained through a previous beacon frame or the like.

1) Solicited Method

Hereinafter, an embodiment for the aforementioned solicited method maybe described first.

According to an embodiment, a non-AP MLD may request information forselecting a link appropriate for an AP MLD before link switching orreconnection. An STA may utilize per-AP data load information orper-link capability information (or information on other links) or thelike to choose an appropriate link.

For example, the per-link capability information may be periodicallytransmitted by being included in a beacon frame or the like.

As another example, the per-link capability information is optionalinformation, and may not be included in the beacon frame transmittedevery period. Alternatively, only information on a link to which the STAis connected or an associated partial link may be received to reduce aframe overhead. Alternatively, when a beacon reception period is longdue to a characteristic of the non-AP MLD (e.g., a low-power device),the non-AP MLD may not receive per-link capability information forselecting a more appropriate link.

In the aforementioned cases, the non-AP MLD may request the latestinformation of per-link capability information and per-link information(e.g., BSS parameter information or operation element information, etc.)of the AP MLD. A link of the per-link capability information andper-link information may include not only a link fortransmission/reception but also other links. For example, a field(A-Control field of the 11ax standard) of a QoS data frame, a managementframe, a probe response/request frame, a PS-Poll frame, a null frame, orthe like may be used to request/transmit the latest information.Alternatively, an additional new frame may be defined torequest/transmit the latest information.

According to an embodiment, in order to request the latest informationof the per-link capability information and per-link information, the STAmay transmit to the AP a request message for requesting informationrequired for link reselection. For example, a probe request frameconventionally defined may be used for the request message. As anotherexample, a new frame may be defined for the request message.

According to an embodiment, through the request message, the STA mayspecify required specific information and request the AP for thespecified information. The specific information to be specified maychange depending on a situation. That is, the STA may request onlyinformation corresponding to a specific link, or may request onlyinformation corresponding to specific capability. For example, theinformation corresponding to the specific link may include informationon BSS load/parameters of the specific link. In addition, theinformation corresponding to capability may include BSS load informationon all links or BSS load information on the specific link. In this case,the AP may transmit only information specified by the STA through theresponse message. A specific embodiment for the specific informationrequest and response may be described according to an embodiment for anIOM definition and operation.

As another example, the STA may request all capability information(e.g., including information on other links) currently owned by the APMLD through the request message.

As described in the aforementioned example, an embodiment fortransmitting all information owned by the AP or an embodiment fortransmitting only specific information specified by the STA may bedefined/configured variously. For example, the AP may transmit allinformation or specified information, based on an additional field, abitmap, or the like to indicate (or transmit) only the specificinformation.

In general, a message for requesting information to the AP MLD may betransmitted through an STA which desires for reconnection, but may alsobe transmitted through any STA (i.e., other STAs) according to asituation (a channel situation or a link situation).

The AP MLD which has received the request message may transmit to thenon-AP MLD a response message (i.e., an information message) includinginformation (e.g., per-link data load information, STA capabilityinformation between links, etc.) requested by the STA. For example, whena probe request frame based on the conventional standard is re-used forthe request message, the AP (or AP MLD) shall respond by using a proberesponse frame as the response message.

In general, the response message may be transmitted through the AP whichhas received the request message, but may also be transmitted to any AP(i.e., other APs) by using a multi-link characteristic.

Optionally, the AP MLD may transmit a “recommended link” element, whichrecommends a link appropriate for the STA, together through the responsemessage including the aforementioned several information (e.g. thelatest information required for link reselection).

In the present specification, a case where the STA of the non-AP MLDrequests information on other APs will be described in detail.

When the STA of the non-AP MLD transmits an MLD probe request frame torequest a peer AP for complete information on other APs, the peer AP isexpected to respond with an MLD probe response frame including thecomplete information on APs, requested by the STA. In this case, thepeer AP may respond with the requested complete information on the APs,included in the complete information on the AP, as follows.

1-1) Method in which the complete information on the peer AP ismandatorily included in the MLD probe response when the STA requests thecomplete information on other APs

In this method, the complete information on the peer AP is includedtogether even if the STA requests the complete information on other APsof the same AP MLD except for the peer AP. An inheritance model is usedin the current 802.11be to reduce an overhead of an MLD probe response.Accordingly, when the STA requests the complete information on otherAPs, the AP may apply the inheritance model if the complete informationon the peer AP is always included. In other words, if the AP MLDincludes information on the peer AP when responding to a request for thecomplete information on specific APs, a value commonly included in thesame MLD may be included as common info in an ML IE, and informationwhich differs for each AP may be included as a non-inheritance elementin a per-STA profile in the ML IE. When the STA requests the completeinformation on several other APs, information which exists identicallymay be configured only one time as common info, thereby reducing anoverall overhead of an MLD probe response frame. In this case, when theSTA does not request the complete information on the peer AP, anoverhead exists to some extent since unrequested information on the peerAP is also included. However, when information on several other APs isrequested, it may be effectively used since the overhead may bedecreased by a greater extent by using the inheritance model.

1-2) Method in which the complete information on the peer AP is notmandatorily included in the MLD probe response when the STA requests thecomplete information on other APs (i.e., method in which only therequested complete information on other APs is included intransmission).

This is a method in which only the requested complete information on APsis transmitted by included in the MLD probe response when the STArequests the peer AP for the complete information on other APs. Thismethod may reduce an overhead by applying an inheritance model when theSTA requests information on the peer AP together. However, when the STArequests only information on other APs of the same AP MLD except for theinformation on the peer AP, the inheritance model is not applicable.Therefore, when the information on the peer AP is not included, anoverhead may be increased to some extent since the inheritance model isnot applied. However, when the STA requests the complete informationonly for a specific AP instead of several APs, the overhead may be smallsince unnecessary information on the peer AP is not included. A methodin which a response is made by including only information on APs,requested by the STA, may be simpler to some extent than the firstmandatory method. However, with the increase in the number of other APsin the same AP MLD for which the STA requests the complete information,the first mandatory method which uses the inheritance model may be moreefficient.

1-3) Method in which the peer AP transmits the complete informationoptionally through a configuration having a small overhead.

In this method, the AP configures and transmits an MLD probe response inan effective manner by comparing a frame overhead which occurs in afirst case (a method in which information on the peer AP is mandatorilyincluded in the response when the STA does not request the informationon the peer AP together) and a second case (a method in which theinformation on the peer AP is not mandatorily included in the responsewhen the STA does not request the information on the peer AP together)according to a configuration of an MLD probe response frame based onAP's common info requested by the STA. In other words, efficiency forapplying the inheritance model is compared according to APs' informationrequested by the STA, and a response is made by configuring a formathaving a smaller overhead. However, in this method, a criterion by whichit is considered as being efficient by comparing the two cases may bedetermined according to an implementation of the AP.

The aforementioned method for several options is a method for a casewhere the STA requests the complete information on other APs, and is notapplicable when the STA requests partial information on other APs sinceinformation on a specific IE is requested. However, when the STA usesone MLD probe request frame to request the complete information on someAPs and request the partial information on some APs, the aforementionedthree methods may be used since the inheritance model is applicable.

The aforementioned solicited method may be used for link switching orreconnection in the STA of the non-AP MLD. For example, when the STA ofthe non-AP MLD desires to reselect a link due to link congestion, theSTA of the non-AP MLD may request BSS parameter information and per-linkBSS load information on the AP MLD connected through the solicitedmethod. The AP which has received this request message may transmit aresponse message including a link and information indicated by the STA.

Hereinafter, the aforementioned request message and response message maybe described as an information request message and an informationresponse message to distinguish from a request message for linkswitching and a response message for the link switching.

Based on information included in the aforementioned information responsemessage, the STA may reselect an appropriate link and request the AP MLDfor link switching or reconnection through the request message for linkswitching. The request message for link switching may includeinformation on an AP or link to which the STA is to be reconnected.

The AP MLD which has received the request message may transmit aresponse message of “accept” when the request is accepted. The AP MLDmay transmit a response message of “decline” when the request isdeclined.

If the request is accepted, after the response message is transmitted,the AP may perform link (re)setup, based on frame exchange through areselected link of the AP. Otherwise, if the request is declined, theSTA may directly use a previously connected link.

An example of the AP MLD and non-AP MLD according to the solicitedmethod may be described in detail with reference to FIG. 19 .

FIG. 19 illustrates an operation of an AP MLD and non-AP MLD for linkswitching or reconnection.

Referring to FIG. 19 , when it is desired to reselect a link to which anSTA 2 of the non-AP MLD is connected, the STA 2 may transmit an inforequest message to the AP MLD through a link 2. The AP MLD which hasreceived this message may transmit an info response message includinginformation required for the link reselection of the non-AP MLD. Basedon information included in the aforementioned info response message, theSTA 2 of the non-AP MLD may transmit a request message for linkswitching (i.e., a link switching request frame) to an AP 2 of the APMLD. Thereafter, the STA 2 may receive a response message for linkswitching (i.e., a link switching response frame) and perform link(re)set-up for link switching.

An embodiment for an information request proposed in the presentspecification may also be used/applied when an STA requests an AP fornecessary information. When information included in a frame (e.g.,beacon) received by the STA from the AP is insufficient, the STA mayrequest the AP for the insufficient information. For example, when theAP transmits only information on a connected link without includinginformation on other links or when the AP transmits only information onwhether the information on other links is updated, the STA may requestthe AP for the insufficient information.

An example of the aforementioned embodiment may be described in detailwith reference to FIG. 20 .

FIG. 20 illustrates an operation of a non-AP MLD for requestinginformation on other APs.

Referring to FIG. 20 , an AP MLD (or AP 1 to AP 3) may transmit onlyinformation on whether information on other APs (i.e., links) is updatedto an STA through a beacon frame. Therefore, an STA 2 may transmit aninfo request message (or info request frame) to the AP2. The STA 2 mayreceive an info response message (or info message), based on the inforequest message. The STA 2 may receive/obtain information on other APs,based on the info response message.

For example, the information on other APs (e.g., BSS load information orthe like) of the AP MLD may not be included in a beacon, or the AP 2 maytransmit only information on whether the information on other APs isupdated (e.g., version/update version).

The STA 2 may require information of the AP 1 (or information on the AP1). The STA 2 may request the required information through the AP 2. TheSTA 2 may obtain the information of the AP 1 through a response messagefor the request. The STA 2 may use the information of the AP 1 toreselect a proper link for link switching. For example, a frame for linkswitching may be configured variously.

Additionally, the aforementioned solicited method may also be used bythe STA to obtain information on APs owned by the AP MLD even beforemulti-link setup. In a multi-link setup process of the non-AP MLD and APMLD, if the number of APs owned by the AP MLD is greater than the numberof STAs owned by the non-AP MLD, STAs of the non-AP MLD shall determinefor which AP of the AP MLD the link will be set up. In this case, theSTA of the non-AP MLD may request the AP of the AP MLD for per-linkspecific information (e.g., BSS load information or the like of APsowned by the AP MLD) in order to know a state for each link before themulti-link setup. For example, the STA may use a probe request as arequest message. As another example, a new frame may be defined for therequest message. The STA may transmit the request message including anindicator (e.g., a request element or an extended request element or aPV2 probe response option element, etc.) for requesting a specificelement or an indicator (e.g., a link ID, etc.) for indicating specificlink information.

For example, the STA of the non-AP MLD may transmit a request messageincluding an instruction which requests current BSS load information foreach of all APs in the AP MLD to be connected. The AP which has receivedthe request message may transmit to the STA a response messagecontaining necessary information (BSS load information on all APs of theAP MLD to which the AP is connected), based on the instruction of theSTA. In this case, the STA which has verified the BSS load informationfor each AP may select a link in an ascending order of BSS load of a BSS(i.e., AP). The STA may indicate a link selected in the multi-linksetup. In other words, information on the link selected in themulti-link setup may be transmitted to the AP.

As such, the STA may use the aforementioned solicited method as a methodfor obtaining information for each AP of the AP MLD in order to select alink to be connected before the multi-link setup.

Hereinafter, a new element/field including information used by the STAof the non-AP MLD to select an appropriate link may be proposed.

For example, a “ratio per link” (element/field) may be proposed. “STAratio per link” may include information on a ratio of the number of STAsconnected for each link. An example of the “STA ratio per link” may bedescribed in detail with reference to FIG. 21 .

FIG. 21 illustrates an example of an STA ratio per link in detail.

Referring to FIG. 21 , the STA ratio per link (element/field) mayinclude information on a ratio or the number of STAs connected for eachlink in all AP MLDs.

For example, when 50 STAs are connected to the AP MLD having 3 links, 10STAs may be connected to a link 1, and 20 STAs may be connected to alink 2. The AP MLD may transmit information on the STA connected foreach link to a non-AP MLD through the STA ratio per link (element/field)as information on a value or ratio (%).

For example, when the information on the STA connected for each link isrepresented as a value, the link 1 may be represented/set to 10, and thelink 2 may be represented/set to 20. Therefore, a value of an STA ratioper link 1 may be set to 10. In addition, a value of an STA ratio perlink 2 may be set to 20.

As another example, when the information on the STA connected for eachlink is represented as a ratio, the link 1 may be represented/set to 20(10/50)%, and the link 2 may be represented/set to 40 (20/50)%.Therefore, the value of the STA ratio per link 1 may be set to 20. Inaddition, the value of the STA ratio per link 2 may be set to 40.

The aforementioned example is for exemplary purposes only, and theinformation on the STA connected for each link may be set variously. Inaddition to the aforementioned example, information on the STA connectedfor each link may be set as a relative value.

Based on the information on the STA connected for each link, the STA mayverify/obtain the number and ratio of the STAs connected for each link,and may use this as information for link selection.

According to an embodiment, in addition to the “ratio per link”(element/field), a variety of information/element/field may be includedin an information response message. For example, the followinginformation/element/field may be included in the information responsemessage.

-   -   BSS load information for each AP    -   STR capability information between links    -   TXOP information for each link    -   NAV information for each link    -   recommended link information (i.e., “recommend link” element)    -   information of ratio of STAs connected for each link (i.e., “STA        ratio per link” element)    -   etc.

In addition to the aforementioned information/element/field, a varietyof information required for link selection may be transmitted by beingincluded in the information response message.

The STA which has received the aforementioned exemplary information mayselect an AP to be switched or reconnected by the STA, based on thereceived information, and then may transmit a request message forrequesting link reconnection. The AP which has received the requestmessage may transmit a response message of “accept” when the request isaccepted. The AP MLD may transmit a response message of “decline” whenthe request is declined.

If the request is accepted, the AP may perform frame exchange through areselected link with the AP after transmission of the response message.Otherwise, if the request is declined, the STA may directly use apreviously connected link.

2) Unsolicited Method

Unlike the solicited method in which the non-AP MLD directly requestsadditional information, according to the unsolicited method, the AP MLDmay transmit the additional information to the non-AP MLD through abeacon frame or an additional frame (e.g., a field (A-control field ofthe 11ax standard) of a QoS data frame, a management frame, an FILSdiscovery frame, an unsolicited probe response frame, a PS-poll frame, anull frame, or the like) without an additional information request ofthe non-AP MLD. As another example, a new frame may be defined as aframe for transmitting the additional information to the non-AP MLD.

For example, when a beacon period is long to some extent, necessaryinformation required for link switching may be insufficient or may notbe the latest information. Therefore, the AP may transmit a frameincluding link capability information on the AP MLD to the non-AP MLD.Thereafter, the non-AP STA may obtain the latest information forcapability of each link of the AP MLD. The frame may be transmittedperiodically or may be transmitted aperiodically.

For example, when the frame is transmitted periodically, the AP maytransmit a frame to share the latest information on the AP everyspecific time interval. In this case, the time interval shall be shorterthan a period of a beacon transmitted by the AP. In addition, when anFILS discovery frame is used as the frame, the frame may be transmittedevery 20 us. As another example, a period agreed by the AP and the STAthrough capability negotiation may be used. For example, a transmissioninterval may be indicated through a “periodic” field and “interval”field/subfield value of an IOM capability element.

As another example, when the frame is transmitted aperiodically, the APmay transmit the frame whenever an event of updating information(capability, BSS parameter, operation element) of the AP occurs.Specifically, for example, changed information may be transmitted to aconnected STA whenever link capability of the AP of the AP MLD changes.In this case, the STA may maintain the latest information for the linkcapability.

According to the aforementioned example, since the non-AP STA does nottransmit a request message for obtaining additional link capability,there is an advantage in that a frame exchange overhead is relativelysmall compared to the solicited method. In addition, since the STA mayreceive updated information whenever critical information is updated,there is an advantage in that information received by the STA is usedusefully.

An example of operations of an AP MLD and non-AP MLD according to theunsolicited method may be described in detail with reference to FIG. 22.

FIG. 22 illustrates an operation of an AP MLD and non-AP MLD for linkswitching or reconnection.

Referring to FIG. 22 , the AP MLD may transmit necessary informationrequired for link reselection to a non-AP through an additional frame(e.g., a PS-Poll frame, a Null frame, etc.), without an additionalrequest message of the non-AP MLD.

According to an embodiment, unlike in FIG. 22 , the AP MLD may transmitinformation on link capability, without an additional request message ofthe non-AP MLD, to the STA through a field of a DL frame (e.g., QoS dataframe) transmitted by the AP MLD to the non-AP MLD. The operation of theAP MLD and non-AP MLD according to the embodiment may be described withreference to FIG. 23 .

FIG. 23 illustrates an operation of an AP MLD and non-AP MLD for linkswitching or reconnection.

Referring to FIG. 23 , an AP 2 may transmit information on other APs (orinformation on other APs) to an STA 2, based on a DL frame (i.e., DL 1).In other words, the DL frame may include information on other APs. Forexample, the information on other APs may be included in an A-Controlfield of the like of the 802.11ax standard. According to theaforementioned embodiment, since the existing DL frame is utilizedwithout an additional message, there is an advantage in that a frameoverhead is decreased. If information is required on a real-time basisdue to a change in critical information on other APs, update informationmay be transmitted through an additional message as in the embodiment ofFIG. 23 .

For example, critical information on the AP may include A to Q asfollows.

-   -   A. Inclusion of a Channel Switch Announcement element    -   B. Inclusion of an Extended Channel Switch Announcement element    -   C. Modification of the EDCA parameters element    -   D. Inclusion of a Quiet element    -   E. Modification of the DSSS Parameter Set    -   F. Modification of the CF Parameter Set element    -   G. Modification of the HT Operation element    -   H. Inclusion of a Wide Bandwidth Channel Switch element    -   I. Inclusion of a Channel Switch Wrapper element    -   J. Inclusion of an Operating Mode Notification element    -   K. Inclusion of a Quiet Channel element    -   L. Modification of the VHT Operation element    -   M. Modification of the HE Operation element    -   N. Insertion of a Broadcast TWT element    -   O. Inclusion of the BSS Color Change Announcement element    -   P. Modification of the MU EDCA Parameter Set element    -   Q. Modification of the Spatial Reuse Parameter Set element

Therefore, the non-AP MLD may obtain the latest link capabilityinformation irrespective of a beam frame period. The non-AP MLD mayselect an appropriate link in link switching, based on receivedinformation. The STA may reselect the appropriate link and request theAP MLD for link switching or reconnection, based on the receivedinformation. The request message may include information on an AP orlink to which the STA is to be reconnected. In addition, the AP MLDwhich has received this message may transmit a response message of“accept” when a request is accepted, and may transmit a response messageof “decline” when the request is declined.

If the request is accepted, after the response message is transmitted,the AP may perform link (re)setup, based on frame exchange through areselected link of the AP. Otherwise, if the request is declined, theSTA may directly use a previously connected link.

3) General Method

According to the general method, a non-AP MLD may request link switchingor reconnection without an additional information request, based oninformation currently owned by the non-AP MLD. Information used in thiscase may include information on an AP MLD and information on a non-APMLD (e.g., per-link STR capability information, link state(enable/disable) information, etc.), included in a previously receivedbeacon or management frame, etc.

Unlike in the solicited method, an STA may directly transmit a requestmessage for link switching or reconnection to the AP MLD without havingto request the AP MLD for an additional information request. The requestmessage may include information on an AP or link to which the STA is tobe reconnected. The AP MLD which has received the request message maytransmit a response message of “accept” when the request is accepted,and may transmit a response message of “decline” when the request isdeclined.

If the request is accepted, the AP may perform frame exchange through areselected link with the AP after transmission of the response message.Otherwise, if the request is declined, the STA may directly use apreviously connected link.

An example of an operation of an AP MLD and non-AP MLD according to thegeneral method may be described in detail with reference to FIG. 24 .

FIG. 24 illustrates an operation of an AP MLD and non-AP MLD for linkswitching or reconnection.

Referring to FIG. 24 , an STA 2 may desire to directly switch a link forthe purpose of guaranteeing QoS. When the STA 2 has informationpreviously received from the AP MLD (e.g., information received througha beacon frame, a management frame, etc.) or has already determined alink to be reconnected, the STA 2 may request the link switching orreconnection without an additional information request.

The STA 2 may transmit a link switching request frame including STAinformation (e.g., STA ID, etc.) and information on a link to beswitched (e.g., a link ID, AP BSS information, etc.). The AP MLD whichhas received this may transmit a link switching response frame of“accept” to an STA 3 through the existing link 2 when the switching isaccepted. Thereafter, the STA 2 of the non-AP MLD may be reconnected toan AP 3 after performing a link (re)setup process.

Signaling for Indicating a Method of Link Switching and Reconnection

In order to indicate the methods proposed above, a mutual agreementprocess may be required through negotiation between an AP MLD and anon-AP MLD. To this end, a signaling method may be proposed to enablethe methods to be proposed in the specification described below.

First, a new element may be proposed to indicate the methods proposedabove. Although an embodiment related to signaling for indicating themethod of link switching and reconnection is described hereinafter, theembodiment may also apply to an embodiment related to signaling forindicating a method of switching and reconnecting an anchored link.

A signaling process for indicating the method of link switching andreconnection may be performed in multi-link setup or after themulti-link setup. In addition, new elements proposed hereinafter may beused in the signaling process for indicating the method of linkswitching and reconnection. For example, the elements may be included ina (re)association frame of the conventional standard or a new frame.

IOM (Information Obtain Method) Capability Element

The IOM capability element may include information on whether a methodof obtaining additional information for a multi-link is enabled. Forexample, an IOM capability value may be present in an element in amessage in a process (e.g., capability negotiation process) in which anAP MLD and a non-AP MLD exchange a message for agreement on an operationin a multi-link setup process. When the IOM capability value is presentin the element in the message, it may imply that IOM capability issupported.

According to an embodiment, when the AP MLD supports the IOM capability,an AP may internally share information on other APs, and may have theinformation on other APs. An MLD in which the information on other APsis not shared cannot support the IOM capability.

According to an embodiment, when a value of the IOM capability elementis set to a first value (e.g., 1), it may imply that the IOM capabilityelement enables the IOM and operates with a specified function.Otherwise, when the value of the IOM capability element is set to asecond value (e.g., 0), it may imply that the IOM capability elementdisables the IOM.

According to an embodiment, the IOM capability element may includevarious fields/elements to indicate various operations. For example, theIOM capability element may also include various fields/elementsdescribed below. However, when the AP MLD requests link switching andwhen the non-AP MLD requests link switching, a field/element to be addedin the IOM capability element may be set differently. In addition, atleast some of the fields/elements added in the IOM capability elementmay be omitted. For example, a field/element including information notnecessarily indicated among the fields/elements to be added in the IOMcapability element may be omitted.

Hereinafter, an example of various fields/elements defined/configured toobtain additional information on a multi-link. The variousfields/elements described below may be configured independently, or atleast two fields/elements may be combined and transmitted throughvarious frames. For example, the various fields/elements described belowmay be included in other elements to perform a defined operation. Asanother example, the various fields/elements described below may be usedas individual elements or may be used by being added in other elementsas independent fields.

Method Type (or Method) Field/Element

A method type field/element (hereinafter, method field/element) mayinclude information on a method of operating an IOM. In other words, themethod field/element may indicate the method of operating the IOM. Forexample, when a non-AP MLD enables an IOM method to obtain informationfrom an AP, the non-AP MLD may indicate a method to be used by selectingthe method among the methods provided above (e.g., the solicited method,the unsolicited method, and the general method).

For example, the solicited method may be indicated/used, based on that avalue of the method field/element is a first value (e.g., 0). Theunsolicited method may be indicted/used, based on that the value of themethod field/element is a second value (e.g., 1). The general method maybe indicted/used, based on that the value of the method field/element isa third value (e.g., 2). Both of the solicited method and theunsolicited method may be indicted/used, based on that the value of themethod field/element is a fourth value (e.g., 3).

As another example, 1 bit may be used for the method field/element. Inthis case, the solicited method may be indicated/used, based on that thevalue of the method field/element is the first value (e.g., 0). Theunsolicited method may be indicated/used, based on that the value of themethod field/element is the second value (e.g., 1).

As another example, 2 bits may be used for the method field/element. Inthis case, it may be indicated that each method is used alone orredundantly.

Link Range Field/Element

When a non-AP MLD requests an AP MLD for information, a range of link tobe requested may be indicated through a link range field/element. Thelink range field/element may include information on whether an STAdesires to request information on all links in an AP MLD or desires torequest information on some links in the AP MLD.

For example, when a value of the link range field/element is a firstvalue (e.g., 0), it may imply that the link range field/element requestsinformation on all links in the AP MLD. When the value of the link rangefield/element is a second value (e.g., 1), it may imply that the rinkrange field/element requests information on some links in the AP MLD.

In this case, when the value of the link range field/element is thefirst value (e.g., 0), since it is a request for all links in the APMLD, additional link indicator (e.g., “link condition” field)information is not necessary. Otherwise, when the value of the linkrange field/element is the second value (e.g., 1), since it is a requestfor information on some links in the AP MLD, link indicator informationis necessary. For example, this field may be used by being included inthe multi-link element defined in the 802.11be. The multi-link elementcurrently defined is as shown in FIG. 25 .

FIG. 25 illustrates an example of a multi-link element added in a proberequest.

As shown in FIG. 25 , when a non-AP MLD transmits a request message forrequesting information on an AP MLD, a “range” field may be used bybeing added in the multi-link element. This is exemplified as shown inFIG. 26 .

FIG. 26 illustrates an example of using a link range field in amulti-link element.

As shown in FIG. 26 , a link range may be used together with an MLD MACaddress field to indicate whether it is a request for information on alllinks in a corresponding MLD or a request for information on some links.In this case, if a value of the field is 0, it means a request for theinformation on all links. Therefore, since additional link indicatorinformation is not necessary, a “per-STA profile (x)” sub-element may beomitted.

In addition, this field may not be included in the multi-link elementdefined in the 802.11be, and may be used by being added in otherelements. This is exemplified as shown in FIG. 27 .

FIG. 27 illustrates an example of a field newly proposed to indicatelink switching and reconnection.

As shown in FIG. 27 , several fields proposed in the presentspecification may be used together to indicate a range and condition ofinformation requested by an STA to an AP MLD in an integrated format asshown in FIG. 27 . Alternatively, when the STA requests the AP MLD forthe information, each of proposed fields may be included independentlyin a request message, and may be omitted if it is not necessary.

Info Range Field/Element

When a non-AP MLD requests information, an info range field may be usedto indicate a range of information.

For example, when a value of the info range field is a first value(e.g., 0), the info range field may indicate that only partialinformation owned by an AP is provided. When the value of the info rangefield is a second value (e.g., 1), the info range field may indicatethat all information (or complete information) owned by the AP isprovided.

According to an embodiment, the info range field may be defined toindicate a request for complete or partial information (elements) ownedby the AP, but an STA may also request more specific information throughan additional subfield. For example, a subfield for indicating a rangeof information to be provided (e.g., all information or partialinformation) may be included in the info range field. For example, thesubfield for indicating the range of information to be provided may bedefined/configured as all/partial subfields.

According to an embodiment, a subfield for indicating whether to provideall information or whether to provide only changed information among theall information may be newly proposed. In other words, the subfieldnewly proposed may indicate whether to provide all information orwhether to provide only changed information among the all information.

For example, the subfield for indicating whether to provide allinformation or whether to provide only changed information among the allinformation may be defined/configured as an only updated subfield.

When the STA desires to receive only the changed information, a value ofthe only updated subfield may be set to 1. In other words, when the STAdesires to receive only the changed information, the STA may set thevalue of the only updated subfield to 1. For example, if the value ofthe only updated subfield is set to 1, according to the solicitedmethod, when the STA requests information, an AP (or AP MLD) maytransmit only changed information (i.e., updated information) among therequested information. As another example, if the value of the onlyupdated subfield is set to 1, according to the unsolicited method, theAP may notify only changed information in an info range configured bythe STA.

According to the example above, although the only updated subfield inthe info range field is restricted in order to receive only the changedinformation, the present disclosure is not limited thereto. In order toreceive only the changed information, an additional field or element maybe defined/configured.

According to the aforementioned embodiment, the info range which may berequested by the STA may be set to updated information or allinformation. In this case, an STA which does not desire a great frameoverhead may request to receive only the changed information. Therefore,there is an advantage in that an overhead is reduced.

Link Condition Field/Element

A link condition field may be used to indicate a requested specificlink. In other words, the link condition field may include informationon the requested specific link. The link condition field may be usedwhen an STA desires to receive only specific link information providedfrom an AP.

The link condition field may be represented by a link identifier (e.g.,link ID, BSS ID). In other words, the link condition field may includeinformation on the link identifier (e.g., link ID, BSS ID). In otherwords, in order to specify a link for obtaining information, the linkidentifier may be used.

For example, when an STA connected to a link 1 desires to request the APfor only information on links 2 and 3, the STA may request the AP forinformation on the links 2 and 3 by indicating the links 2 and 3 in thelink condition field. For example, when the value of the info rangefield is 1, all information corresponding to the links 2 and 3 may betransmitted. As another example, when the value of the info range fieldis 0, partial information specified by the STA in the links 2 and 3 maybe transmitted. According to an embodiment, the partial informationspecified by the STA may be determined through an info condition fielddescribed below.

According to an embodiment, when a value of the link condition field isabsent or 0, the AP may determine that there is no link condition.Therefore, the AP may provide/transmit information on all links to theSTA.

Info Condition Field/Element

An info condition field may be used to indicate a requested specificinformation type. In other words, the info condition field may be usedwhen an STA desires to receive only specific information provided by anAP.

For example, the info condition field may be used only when the inforange field is set to 1. As another example, the info condition fieldmay also be used by the STA to indicate specific information even ifthere is no info range field.

For example, in the info condition field, information (e.g., BSS load,STR capability, etc.) specifiable by the STA may be represented by abitmap. For example, a type of information provided by the AP, a methodor order of indication in a bit, or the like may be configuredvariously.

According to an embodiment, the info condition field may be usedtogether with the aforementioned link condition field. According to anembodiment, the info condition field may be used to transmit requestinformation of various conditions to the STA (or AP), based on acombination of various fields/elements.

In this regards, an element of the conventional standard may be re-usedso that the STA requests to indicate specific information. For example,a request IE or an extended request IE may be used. Element informationfor this is as shown in FIG. 28 and FIG. 29 .

FIG. 28 illustrates an example of a request IE format.

FIG. 29 illustrates an example of an extended request IE format.

Elements of FIG. 28 and FIG. 29 may be used to request specificinformation in a probe request frame or an information request frame.When an STA indicates a list of information of which a response isdesired by using requested element IDs, an AP transmits a probe responseframe or information response frame including information correspondingthereto. Therefore, in the present specification, this element may bere-used as an indicator for requesting specific information, and mayalso be used to request desired information on a desired link togetherwith a link identifier. For example, an element ID for BSS loadinformation may be indicated in the request element mentioned in FIG. 28and FIG. 29 , and when information on an AP 2 is desired, only BSS loadinformation on the AP 2 may be requested upon indicating this with alink identifier. The element ID information may be used to indicatespecific information on a specific AP with various combinations togetherwith link identifier information. Even if a new frame is defined in thepresent disclosure for an information request instead of the existingframe, the request element and extended request element of FIG. 28 andFIG. 29 may be re-used.

In addition, in the conventional standard, a PV1 probe response optionelement is provided to request specific information, and this elementmay be re-used by using a method of indicating the specific information.For frequently used information, a method in which an STA uses desiredinformation to request optional information as a probe request is usedto indicate each information with a probe response option bitmap asdescribed below. However, in case of 11be, since multi-link informationshall be provided by considering an MLD, the STA may request specificinformation on a specific link in various combinations by using a linkidentifier together with a bitmap indicator described below. However, inthis case, since optional information (e.g., STR capability) newlydefined may be present together with the multi-link in the 802.11be,when the PV1 probe response option element is re-used, a bitmap forinformation which is newly defined in the 11be or which is to beadditionally obtained shall be newly defined or additionally defined.

FIG. 30 illustrates an example of a PV1 probe response option elementformat.

Transmission Periodic Field/Element

When an STA desires to receive information provided in the unsolicitedmethod, whether a message including the information is to be receivedperiodically or received aperiodically may be indicated through aperiodic field.

For example, when the STA desires to receive the informationaperiodically, whenever information on other APs is updated, the AP maynotify about the updated information.

As another example, when it is indicated that the STA is to receive theinformation periodically, the STA may receive a message including theinformation with an interval of a set period.

According to an embodiment, a transmission periodic field may be set to1 bit. When a value of the transmission periodic field is set to 1, theSTA may receive/obtain information through a periodic method in which amessage is received periodically. When the value of the transmissionperiodic field is set to 0, the STA may receive/obtain informationthrough a method in which a message is received aperiodically.

Transmission Interval Field/Element

According to an embodiment, when an STA desires to receive informationon other APs periodically, the STA may directly set a period thereof.The STA may transmit information on a period for receiving informationon other APs, based on a transmission interval field. However, theperiod shall be set to be shorter than a beacon transmission period. Forexample, when an FILS discovery frame is used, a period thereof shall beset to 20 us.

As described above, it may be defined as an additional field in anelement indicating a transmission period, or may also be defined as asubfield in a transmission periodic field.

According to an embodiment, the field/element defined/configured toobtain the additional information for the multi-link is not limited tothe aforementioned field/element, and various fields/elements may befurther configured.

Accordingly, the MLD (AP MLD or non-AP MLD) may indicate IOM capabilitythrough negotiation between the AP MLD and the non-AP MLD by using atleast one of the aforementioned elements/fields in the multi-link setupprocess. In addition, after the multi-link setup is complete, the MLDmay update content agreed between the MLDs through additional messageexchange.

According to an embodiment, when the IOM capability is enabled, the APMLD and the non-AP MLD may operate based on an embodiment for linkchanging and reconnection.

Hereinafter, an example of the operation of the AP MLD and non-AP MLDmay be described when the IOM capability is enabled. For example, thenon-AP MLD may transmit the aforementioned fields/elements to the AP MLDto request additional information for a multi-link. The non-AP MLD maytransmit an IOM capability element including the aforementionedfields/elements to the AP MLD. The fields/elements are included in theIOM capability element for exemplary purposes only, and may also betransmitted as independent fields/elements.

For example, in the multi-link setup process, the non-AP MLD maytransmit an IOM capability element including “Method field=0” and “Inforange field=1” to the AP MLD, and may agree on this with the AP MLD. Inthis case, after the multi-link setup, the non-AP MLD operates with thesolicited method, and when information is requested, may requestinformation on a multi-link including all information included in abeacon (e.g., information on other APs). Therefore, the AP MLD mayprovide/transmit information on a link as a response message, only whena request message is received from the STA. When the request message isreceived, the AP MLD may transmit to the STA a response messageincluding information on all links in the AP MLD. The information on alllinks in the AP MLD may include all information included in the beacon.

As another example, the non-AP MLD may transmit to the AP MLD an IOMcapability element including “Method field=1”, “Info range field=0”,“Link range=Link id 2”, “Info condition field=(a value indicating a BSSload through a bitmap)”, and may agree on this with the AP MLD. In thiscase, after the multi-link setup, the non-AP MLD may operate with theunsolicited method. Accordingly, the AP may transmit BSS loadinformation on a link 2 to the STA through an additional message,without having to use an additional request message.

As another example, the non-AP MLD may transmit to the AP MLD an IOMcapability element including “Method field=0”, “Info range field=0”,“only updated field or subfield=1”, “Info condition field=(a valueindicating a BSS load through a bitmap)”, and may agree on this with theAP MLD. In this case, after the multi-link setup, the non-AP MLD mayoperate with the solicited method. Accordingly, the AP MLD (or AP) maytransmit a response message to the STA by including only updated(changed) information among BSS load information on all APs of theconnected AP MLD when the STA requests information.

The present specification proposes several options for new elements sothat an STA requests partial information (i.e., target information) onother APs of a connected AP MLD.

FIG. 31 illustrates an example of an MLD request element.

Referring to FIG. 31 , “the number of Link ID” is a field for indicatingthe number of APs (i.e., links) requested when an STA requestsinformation on a specific AP.

“Link ID” is a field including APs' indicator information requested bythe STA.

For example, when the STA transmits a probe request frame including theaforementioned MLD request element, an AP which has received the requestmessage responds with a probe response including complete information onAPs indicated in a corresponding element. When the STA desires torequest partial information instead of the complete information on theindicated APs, if the probe request frame is transmitted by including arequest element or extended request element defined in the conventionalstandard together with the MLD request element, an AP which has receivedthis responds with a probe response including only information indicatedin the request element or extended request element.

Additionally, a new element of FIG. 32 is also proposed.

FIG. 32 illustrates another example of an MLD request element.

Referring to FIG. 32 , “the number of Link ID” is a field for indicatingthe number of APs (i.e., links) requested when an STA requestsinformation on a specific AP.

“Link ID” is a field including APs' indicator information requested bythe STA.

“Requested Element IDs/Requested Element ID extensions” is a fieldincluding element ID information of requested information when the STArequests specific information (i.e., element). This field includes onlyelement ID information when an element ID corresponds to 0 to 254, andif it is a value greater than or equal to 255, this is recognized as anextended element ID and thus requested element ID extensions informationshall be also be included together. In this case, informationcorresponding to “Requested Element IDs/Requested Element ID extensions”may be defined in the form of a field, but may also be included in anMLD request element in the form of a sub-element by being defined as anew element as shown in FIG. 33 . The new element for this may bedefined as shown in FIG. 33 . A corresponding element may be indicatedas one element without distinction of the existing request element orthe extended request element, thereby advantageously reducing anoverhead.

FIG. 33 illustrates an example in which a new element is defined basedon an MLD request element.

For example, when an STA transmits a probe request frame including theaforementioned MLD request element, an AP which has received a requestmessage responds with a probe response including information on APsindicated in a corresponding element.

Referring to FIG. 33 , the AP recognizes information requested by theSTA as complete or partial information according to whether a “RequestedElement IDs/Requested Element ID extensions” field is omitted in acorresponding element. Element ID value information defined in thestandard is defined in the 802.11 standard. In addition, the definitionon the “Requested Element IDs” and “Element ID extensions” mentioned inthe present specification is the same as in the conventional standard.

For example, if the STA requests the AP for information on the AP orother APs, the probe request frame is transmitted by including theaforementioned MLD request element. The AP which has received thisresponds with a probe response frame including only informationrequested through the “Requested Element IDs/Requested Element IDextensions” field among information on APs requested through the “LinkID” field.

In this case, when the STA performs transmission by omitting the“Requested Element IDs/Requested Element ID extensions” field, an APwhich has received this responds with a probe response frame includingcomplete information on APs requested through the “Link ID” field.

The format proposed above may request only the same information for alllinks.

However, the STA may optionally request different information for eachlink. Several options for this are proposed in the presentspecification.

First, a format for requesting different information for each link isadditionally proposed.

FIG. 34 illustrates another example of an MLD request element.

As shown in FIG. 34 , this is a method in which the existing Requestelement or/and Extended Request element information is included andindicated for each link in an MLE request element in order for an STA torequest different information for each link. In this case, a new fieldor element “The number of Elements” is defined to notify a length ofelement to be requested. This information implies the number of elementsrequested for Link ID(x).

An AP which has received this verifies information requested differentlyfor each link, based on the MLD request element, and responds thereto byincluding the information in a response frame.

In this case, an embodiment for a case where the field proposed in thepresent disclosure is used instead of the existing request elementor/and extended request element may be as shown in FIG. 35 . Each fieldor element may be optionally omitted.

FIG. 35 illustrates another example of an MLD request element.

Second, a format in which common information requested identically forall links and link specific information requested differently for eachlink are identified when an STA requests information is proposed asshown in FIG. 36 .

FIG. 36 illustrates another example of an MLD request element.

As shown in FIG. 36 , when a request element or/and extended requestelement is included before the number of link ID field, this meanselements for common information commonly requested for links indicatedthereafter, and information arranged subsequent to the number ofelements together with Link ID(x) subsequent to the number of link IDfield means element information requested for each link. Each field orelement may be optionally omitted.

In this case, an embodiment for a case where the field proposed in thepresent disclosure is used instead of the existing request elementor/and extended request element may be as shown in FIG. 37 . Each fieldor element may be optionally omitted.

FIG. 37 illustrates another example of an MLD request element.

As shown in FIG. 37 , when a request element or/and extended requestelement is included before the number of link ID field, this meanselements for common information commonly requested for links indicatedthereafter, and information arranged subsequent to the number ofelements together with Link ID(x) subsequent to the number of link IDfield means element information requested for each link. Each field orelement may be optionally omitted.

Fourth, common information requested identically for all links when theSTA requests information is used to indicate as shown in FIG. 38 , as anadditional request element or extended request element together with theMLD request element.

FIG. 38 illustrates an example of a field for requesting commoninformation.

This is a method in which, when an STA requests information on severallinks of an AMP MLD through a request frame, information which iscommonly requested is indicated through the existing request or/andextended request element, and information requested differently for eachlink is indicated through an MLD request element. In this case, a formatof the MLD request element may be defined in various forms. An AP whichhas received this request message recognizes information included in therequest or/and extended request element as information requestedcommonly for a link indicated in the MLD request element, and transmitsa response message including corresponding element information on alllinks indicated in the MLD request element. Additionally, when the STArequests different information for each link, the AP transmits theresponse message including the information, based on informationindicted for each link in the MLD request element.

A method in which an STA requests partial information on other APs of aconnected AP MLD by using a multi-link (ML) IE defined in the 802.11bestandard is proposed.

FIG. 39 illustrates an example of an ML IE format defined in 802.11be.

A multi-link (ML) information element (IE) is defined as shown in FIG.39 in order to define information for each link. An element or a fieldmay be added according to a function proposed at a later time. Severalinformation on a corresponding link may be included in a per-STA profile(x) sub-element. The sub-element includes a corresponding link IDthrough the per-STA control field and content for an information rangeincluded in the sub-element through a per-STA control field, andarranges information (element) corresponding to information requested byan STA at a later time. In this case, in the presence of non-inheritanceinformation, a non-inheritance element may be used to include theinformation. A complete profile in the per-STA control sub-element is afield for identifying whether the included information is completeinformation or partial information on a corresponding link.

Accordingly, the ML IE may be included in a request frame (e.g., proberequest frame), so that the STA utilizes it for a partial informationrequest of other APs. To this end, various options are proposed.

The following restriction element is defined in the presentspecification in order to use the ML IE for MLD probing. When the STAuses the ML IE in the probe request frame for MLD probing, elementinformation (e.g. Element x, . . . , Element n) provided in the per-STAprofile (x) may be omitted in transmission to reduce an overhead(However, the element information shall be included when the ML IE isused in an association request/response frame used for association).When information requested by the STA is complete information on a link,a complete information bit is indicated through the per-STA controlfield and is transmitted by omitting a subsequent element informationlist. Otherwise, a partial information bit is indicated through theper-STA control field, and information on an element ID requested at alater time is added. Several options for a case where the STA requestspartial information on a specific element, not the complete information,is defined below in a greater detail.

As described above, information included in the ML IE defined in the802.11be may vary depending on whether a corresponding element isincluded in an association frame or a probe frame and whether acorresponding frame is a request or a response. For example, when theSTA performs the probe request, if the ML IE is used, elements includingseveral information in the per-STA profile (X) may be omitted, andotherwise, element information shall be included. Accordingly, a controlfield for indicating this is proposed.

At present, multi-link element and multi-link control field formatsdefined in the 802.11b standard are as shown in FIG. 40 .

FIG. 40 illustrates an example of a multi-link element format andmulti-link control field format.

In this case, a field for indicating a form of a frame including acurrent multi-link element is added in a multi-link control fieldelement. The proposed field is defined as an “Elements per-STA Present”.A name of the field may be re-defined optionally. The field indicates apresence or absence of element list information for each STA, requestedby the current ML IE. When a corresponding value is 1, it means thatelement subsequent to the Per-STA Control field is included in thePer-STA Profile (x) field, and when the value is 0, it means thatelement information subsequent to the Per-STA Control field is omittedin the Per-STA Profile (x) field. An embodiment thereof is as shown inFIG. 41 .

FIG. 41 illustrates an example of a multi-link control field format.

Additionally, as described above, information included in the ML IEdefined in the 802.11be may vary depending on whether a correspondingelement is included in an association frame or a probe frame and whethera corresponding frame is a request or a response. Accordingly, a fieldcapable of indicating this is proposed. The field is included in the MLIE of the request/response frame to indicate a frame type currentlytransmitted by the STA. Accordingly, an element configured additionally(an element configured with 0 or a variable) may vary in content or anarrangement order.

“frame type”: an indicator which means a frame type transmittedcurrently by the STA. It indicates a type of a frame in which a currentML IE is included according to a value of a corresponding field. Forexample, it may be indicated by being classified into “0: associationrequest, 1: association response, 3: probe request, 4: probe response”or the like. This may be represented by an integer value, but may alsobe represented by a bitmap. In addition thereto, MLD probing configuredin the 802.11be may be additionally classified into: “5: MLD Proberequest frame, 6: MLD Probe response frame” or the like. As such, thisis an indicator for indicating that an element configuration of the MLIE varies depending on the frame type. Each frame type may be arrangedin the form of subfields in the “frame type” field, and may beconfigured to indicate a frame type when it is 1.

In this case, it may be classified again into several subfields in the“frame type” according to several functions of the transmitted frame.Therefore, a “request type” which is a subfield classified according tothe purpose of a frame in the “frame type” is defined in the presentspecification. The “request type” subfield is classified morespecifically according to a message format classified as the “frametype”, and may be classified according to the purpose of the framecurrently transmitted. For example, in the “frame type”, when an MLDprobe request frame is transmitted to request complete or partialinformation on a specific AP, the “frame type” field is set to an MLDprobe request frame(field=5). However, whether requested information iscomplete information or partial information or, when the partialinformation is requested, which specific information (e.g., criticalupdate-related information, link subset information, which is not setup, for link re-setup, etc.) is requested by corresponding informationmay be classified more specifically as the “request type”. If the “frametype” is set to a (re)association request frame for link switching for aspecific AP, the “frame type” field is set to the (re)associationrequest frame (For reference, since all frames are classified as thesame basic type except for the MLD probe request frame in the current802.11be, the (re)association request frame will be classified as thebasic type, but the classification of the frame type may change in thefuture). However, this may be indicated in the “request type” subfieldaccording to the purpose of requesting a frame (e.g., TID-link mapping,link switching between MLDs, link switching in the same MLD). A non-APSTA or AP which has received this may recognize the purpose of the frametransmitted by the STS more specifically through a subfield valuetransferred together with a type of the currently received frame, andmay transmit a response frame including proper information.

Several format options and operations for an ML IE for a case where theSTA requests partial information on a specific element, not completeinformation, are proposed as follows.

First, there is a method in which transmission is performed by includinga request element or/and extended request element for indicatinginformation to be requested by an STA to a corresponding AP in theper-STA profile (x) in the existing ML IE.

An AP which has received a request message indicating correspondinginformation may know partial information on a link to be requested bythe STA through ML IE information, and transmits a response frame (e.g.,probe response frame) including the corresponding information. In thismethod, the STA indicates whether a link ID to be requested andinformation currently requested are complete information or partialinformation through the per-STA control field in the per-STA profile (x)in the ML IE, and additionally indicates specific information to berequested through the request element or/and extended request element.The STA may request desired specific information for each link by usingthe format of FIG. 42 . If the request element or/and extended requestelement is omitted, it means that complete information on acorresponding AP is requested. However, element information arrangedsubsequent to the per-STA control field may be optionally omitted asdescribed above.

FIG. 42 illustrates an example of an ML IE format.

Second, there is a method in which transmission is performed byincluding a requested element IDs/requested element ID extensions fieldfor indicating information to be requested by an AP to a correspondingAP in the per-STA profile (x) in the existing ML IE. A correspondingfield is defined in FIG. 43 as a field proposed in the presentspecification.

FIG. 43 illustrates another example of an ML IE format.

An AP which has received corresponding information may know partialinformation on a link to be requested by the STA through ML IEinformation, and transmits a response frame (e.g., probe response frame)including the corresponding information. In this method, the STAindicates whether a link ID to be requested and information currentlyrequested are complete information or partial information through theper-STA control field in the per-STA profile (x) in the ML IE, andadditionally indicates specific information to be requested through therequested element IDs/requested element ID extension field. If therequested element IDs/requested element ID extensions field is omitted,it means that complete information (i.e., all elements information) of acorresponding AP is requested. An embodiment of a corresponding formatis as follows. However, element information arranged subsequent to theper-STA control field may be optionally omitted as described above.

The format of FIG. 43 has an advantage in that element indicationinformation defined in the 802.11 standard is transmitted as one pieceof information without having to be identified whether it is the requestelement or/and extended request element, thereby reducing a defaultfield overhead (e.g., element ID, length) or the like.

Third, there is a format in which an STA performs transmission byincluding the request element or/and extended request element toindicate information to be requested to each AP, so that a request ismade by identifying link specific info and common info which is to berequested commonly for all APs by the STA are requested. The format isdefined in FIG. 44 .

FIG. 44 illustrates another example of an ML IE format.

When an STA requests information of each of APs through a request frame(e.g., probe request frame), some pieces of information may beidentically requested, and the other pieces of information may berequested such that information differs for each AP. A format forindicating this is defined and an embodiment thereof is proposed. Asshown in FIG. 44 , an indicator for indicating the same informationrequested by the STA with respect to APs requesting information throughthe request frame uses a request or/and extended request elementtogether with the ML IE in the request frame, and an indicator forindicating different information requested for each AP uses a requestor/and extended element in the per-STA profile (x). However, elementinformation arranged subsequent to the per-STA control field may beoptionally omitted as described above.

For example, the STA may perform transmission in such a manner thatinformation (e.g., Element 5=11) corresponding to a TIM element isindicated in the probe request frame as a request element, “Link ID=1,Complete Profile=0 (otherwise, if the value is 1, it means a request forall elements information)” is indicated in a per-STA control of theper-STA profile (x) in the ML IE, information (e.g. Element ID=11)corresponding to a BSS load element is indicated in the request element,“Link ID=2, Complete Profile=0” is indicated in a per-STA control of aper-STA profile (y), and information (e.g. Element ID=255, Element IDextension=56) corresponding to a non-inheritance element is indicated inthe extended request element. In this case, the AP responds with theprobe response frame including the following information.

-   -   TIM element information on Link 1, Link 2    -   BSS load element information on Link 1    -   Non-inheritance element information on Link 2

The STA may request different information for each link, by classifyinginformation requested according to an arrangement of an element in theframe into common information or link-specific information.

As such, in the 802.11be, an inheritance model may also be applied forthe ML probe request frame. When the STA transmits the ML probe requestincluding the (extended) request element as described above, such apartial information request is accepted by a peer AP as a commoninformation request for all APs since the inheritance model is alsoapplied to not only the peer AP but also APs requested through an ML IE(i.e., probe request variant multi-link element). Accordingly, when aprobe request frame including the (extended) request element outside theML IE is received from the STA as shown in FIG. 44 , it is interpretedas a common information request for the peer AP and the requested APs(APs indicated for an information request of other APs in the ML IE),and an ML probe response may be provided as a response by verifyingrequested information indicated by the (extended) request element and byallowing the per-STA profile to include information corresponding toeach AP in the ML IE (e.g., basic variant multi-link element).

Fourth, there is a format in which an STA performs transmission byincluding the request element or/and extended request element in themulti-link element to indicate information to be requested to each AP,so that a request is made by identifying link specific info and commoninfo which is to be requested commonly for all APs by the STA arerequested. The format is defined in FIG. 45 .

FIG. 45 illustrates another example of an ML IE format.

When an STA requests information of each of APs through a request frame(e.g., probe request frame), some pieces of information may beidentically requested, and the other pieces of information may berequested such that information differs for each AP. A format forindicating this is defined and an embodiment thereof is proposed. If therequest or/and extended request element is included together with themulti-link element in the request frame (e.g., probe request), thismeans that the STA requests partial information on a link (i.e.,associated AP) to which the STA is connected. Upon requestinginformation on APs not corresponding to a link of the STA among APs ofan AP MLD to which the STA is connected, indication information thereofincludes an ML IE (multi-link element). Accordingly, when a requestor/and extended request element is included in the ML IE before theper-STA profile (x) element, information requested commonly for otherAPs (APs not corresponding to the link of the STA among APs included inthe AP MLD to which the STA is connected) of the AP MLD requested by theSTA through a corresponding element may be indicated. The informationrequested commonly for other APs may be indicated through the requestor/and extended request element in the ML IE, and the informationrequested differently for each of other APs may be indicated by addingthe request or/and extended request element subsequent to the per-STAcontrol field in the per-STA profile (x). When an indicator of an APcorresponding to a link of the STA, not other APs, is included in theper-STA profile (x) in the ML IE, the STA may also obtain information onan AP corresponding to the link of the STA through the ML IE. In thiscase, the request or/and extended request element included together withthe ML IE to request partial information on the AP corresponding to thelink of the STA may be omitted.

However, element information arranged subsequent to the per-STA controlfield may be optionally omitted as described above.

Fifth, the STA may request some pieces of complete information or somepieces of partial information on a peer AP (i.e., transmitting link) andother APs (i.e., other links) through the MLD probe request. Severalcases and embodiments related thereto are as follows.

1) When complete information is requested for the peer AP, and completeinformation is also requested for other APs

An EHT non-AP STA is able to transmit a message for requesting completeinformation on the peer AP and other APs by using one probe requestframe.

FIG. 46 illustrates an example of a probe request frame including an MLIE format.

Referring to FIG. 46 , when complete information is requested for thepeer AP, a complete information request for other APs is indicated bysetting a complete profile subfield in the per=STA control field in theper-STA profile of the multi-link element (i.e., probe request variantmulti-link element) to 1, without having to include the (extended)request element in a core of probe request frame (frame body of theprobe request frame).

2) When complete information is requested for the peer AP, and completeor partial information is requested for other APs

2) When complete information is requested for the peer AP, and completeor partial information is requested for other APs

The EHT non-AP STA is able to transmit a message for requesting completeinformation on the peer AP and requesting complete or partialinformation on other APs indicated through the ML IE by using one proberequest frame.

FIG. 47 illustrates another example of a probe request frame includingan ML IE format.

Referring to FIG. 47 , when complete information is requested for a peerAP, an (extended) request element is not included in a core of proberequest frame, and when partial information is requested for other APs,a partial information request is indicated for other APs by includingthe (extended) request element in a per-STA profile of a multi-linkelement (i.e., a probe request variant multi-link element) and bysetting a ‘complete profile’ subfield in the ‘per-STA control’ field to0. In this case, when it is desired to request complete information onother APs, the ‘complete profile’ subfield in the ‘per-STA control’field is set to 1 without the (extended) request element in the per-STAprofile. As such, for other APs, a request of complete information orpartial information is possible for each AP with one probe requestframe.

3) When partial information is requested for the peer AP, and completeor partial information is requested for other APs

The EHT non-AP STA is able to request partial information on the peer APby using one probe request frame and to request complete or partialinformation on other APs indicated through the multi-link element.

FIG. 48 illustrates another example of a probe request frame includingan ML IE format.

Referring to FIG. 48 , when partial information is requested for a peerAP, an (extended) request element is included in a core of probe requestframe, and when complete information is requested for other APs, acomplete information request may be indicated for other APs without the(extended) request element in a per-STA profile of a multi-link element(i.e., a probe request variant multi-link element) and by setting a‘complete profile’ subfield in the ‘per-STA control’ field to 1.

In this case, when it is desired to request partial information on otherAPs, the ‘complete profile’ subfield in the ‘per-STA control’ field isset to 0 by including the (extended) request element in the per-STAprofile. In a case where the inheritance model is applied to the MLDprobe request, if the same information is requested for the peer AP andthe AP (x) (i.e., link) indicated in the per-STA profile (x) as partialinformation, the (extended) request element in the per-STA profile (x)may be omitted. That is, the (extended) request element is included inthe per-STA profile (x) only when the (extended) request elementincluded in the core of probe request frame corresponds to thenon-inheritance element, and otherwise, may be omitted.

An embodiment in which the inheritance model is applied to the MLD proberequest is as shown in FIG. 49 .

FIG. 49 illustrates another example of a probe request frame includingan ML IE format.

Referring to FIG. 49 , when an EHT non-AP STA requests partialinformation on a peer AP through an MLD probe request, an (extended)request element is included in a core of probe request frame. In thiscase, when partial information different from that of the peer AP isrequested for some APs (i.e., per-STA profile (x)) among APs indicatedby a multi-link element, different information may be requested byincluding the (extended) request element corresponding to thenon-inheritance element in the per-STA profile (x). In this case, acomplete profile value of the per-STA control field is set to 0.

Alternatively, when partial information which is the same as that of thepeer AP is requested for some APs (i.e., per-STA profile (y)) among theAPs indicated by the multi-link element, the (extended) request elementin the per-STA profile (y) is omitted. In this case, the completeprofile value of the per-STA control field is set to 0. As such, in acase where the inheritance model is applied to the MLD probe request,when the EHT non-AP STA requests the peer AP for Element (a) and Element(b) and requests the AP (x) indicated by the per-STA profile (x) forElement (a) and Element (c), there is information (e.g., Element (a))requested identically to the peer AP and the AP (x) but differentinformation (e.g., Element (c)) is also included. Therefore, in orderfor the AP to identify this, an (extended) request element indicating aninformation request for Element (a) and Element (c) shall be included inthe per-STA profile (x). (In case of applying the inheritance model,when the (extended) request element is present in the per-STA profile(x), even if there is partial information requested redundantly by thepeer AP, this is recognized as a non-inheritance element. Therefore, ifit is not the case of requesting the same partial information as thepeer AP, all element information requested for an AP (e.g., AP (x))indicated through the per-STA profile (x) shall be indicated in the(extended) request element included in the per-STA profile (x)irrespective of partial information requested for the peer AP). However,when the EHT non-AP STA requests the peer AP for Element (a) and Element(b) and requests the AP (x) indicated by the per-STA profile (x) for thesame Element (a) and Element (b), since the same information isrequested for the peer AP and the AP (x), the ‘complete profile’subfield in the per-STA profile (x) may be set to 0 by applying theinheritance model, and the (extended) request element indicating aninformation request for Element (a) and Element (b) may be omitted.

In this case, when the complete profile value of the per-STA controlfield is set to 1, it means a complete information request for the AP(y), instead of applying the inheritance model to the requestinformation on the peer AP. That is, in the content of the partialinformation request for the peer AP, the complete profile value of theper-STA control field shall be set to 0 in order to apply theinheritance model to the multi-link element.

The STA may request different information for each link, by classifyinginformation requested according to an arrangement of an element in theframe into common information or link-specific information.

To this end, additionally, a new field for indicating whetherinformation requested by a corresponding ML IE in the multi-link controlfield identifies common information is proposed. As such, the STA mayrepresent common information on a corresponding link according to anarrangement of the request element or/and extended request element. Therequest element or/and extended request element may be present in therequest frame according to whether the common information is requested,before the per-STA profile (x) in the ML IE. Accordingly, a controlfield for indicating this is proposed as shown in FIG. 50 .

FIG. 50 illustrates an example of a multi-link control field format.

A field of FIG. 50 may be defined such as a ‘common info present’ field,and a term thereof may be defined as another term at a later time. In acase where the field is indicated with 1, when information on other APsis requested to an AP MLD, an STA transmits to the AP MLD a requestelement or/and extended request element which means the same informationrequest, by including this element before a per-STA profile (x) element.In addition, link-specific information requested differently for each APis indicated through the request element or/and extended request elementincluded in the per-STA profile (x) element. In a case where the fieldis indicated with 0, it means that there is no information requested bythe STA identically for other APs, and means that there is no additionalrequest element or/and extended request element before the per-STAprofile (x) element.

An embodiment for this is as follows.

An STA may request an AP of an AP MLD partially only for critical updateinformation. To this end, two options are proposed. In this case, the APmay be all APs (reporting AP and reported AP) which are obtainable bythe STA through a beacon. The reported AP means other APs which areobtainable by the STA through an RNR element of the beacon, and may benot only other APs in the same AP MLD as the reporting AP but also otherAPs corresponding to a TxBSSID group, other APs corresponding to anon-TXBSSID group, or the like. In other words, the STA may requestcritical update information on all other APs capable of obtaining changesequence number (CSN) information through the beacon (For reference, itis agreed in the 802.11be to include change sequence field informationon other APs in the RNR element of the beacon frame).

First, there is a method in which a ‘critical update request’ field isnewly defined for a request of critical update information on other APs.

-   -   ‘Critical update request’ field: a field which requests only        system information defined as critical update of an AP. It may        be used together with a link indicator and may be used when        system information defined as critical update of a specific link        is requested.

When the STA requests information on other APs of the AP MLD, if arequest frame (e.g., probe request frame) is transmitted together withlink indicator information by setting a field value thereof to 1, an APwhich has received this responds with a response frame includingcritical update information on the indicated link. In this case, thecritical update information means several system information (a)Inclusion of an Extended Channel Switch Announcement, b) Modification ofthe EDCA parameters, c) Modification of the S1G Operation element)defined as critical update in the system information update procedure ofthe conventional 802.11 standard. However, in case of a later version,i.e., 802.11be, new information may be additionally defined in additionto system information predefined conventionally for the critical update,and critical update information mentioned in the present specificationmeans information including the critical update information newlydefined in the 802.11be. If a corresponding field value is set to 0 intransmission, the AP responds with a response frame as in theconventional operation. The proposed field may be included in anyelement in the request frame, and may be used by being included in theaforementioned MLD request element or ML IE. An embodiment for this isas shown in FIG. 51 .

FIG. 51 illustrates an example in which a critical update request fieldis included in an ML IE format.

Referring to FIG. 51 , when an STA requests information on specificlinks by using an ML IE in a probe request, information corresponding toa specific link may be requested through a per-STA profile (x). In thiscase, when a ‘critical update request’ field newly defined in a per-STAcontrol in the per-STA profile (x) is included and set to 1 intransmission, an AP responds with a response frame including currentsystem information defined as critical update for a link indicated inthe per-STA profile (x). In this case, a non-AP STA of a non-AP MLDperforms transmission by setting a ‘critical update request’ field valueto 1 to request critical update information through an MLD proberequest, change sequence number (CSN) information (e.g., change sequenceelement, change sequence field, etc.) for each non-AP STA of the non-APMLD may be included together in transmission, or may be omitted intransmission according to an implementation of the STA. In this case, ifcritical update information on APs is requested by using the MLD proberequest (i.e., ‘Critical update request’ field=1), an additionalindicator is not required in case of using the change sequence elementwhen CSN information is included (since the AP is capable of verifyingan element ID of the change sequence element to verify a presencethereof). However, if the change sequence field is used as the CSNinformation, there is a need to additionally defined a (sub)field (e.g.,‘CSN presence’ subfield) to indicate whether the change sequence fieldis present. Accordingly, an indicator for indicating whether CSNinformation is present in the per-STA profile in the ML IE isadditionally proposed in the present specification.

-   -   ‘CSN Presence’ (sub)field: a field for indicating that a change        sequence field is present. When a value thereof is set to 1, it        indicates a presence of the change sequence field, and when the        value is set to 0, it indicates an absence of the change        sequence field.

-> This field may be used together with the ‘critical update request’field when the STA requests critical update information on other APs(For example, the ‘CSN presence’ (sub)field may be used together withthe ‘critical update request’ (sub)field in the per-STA control field ofthe per-STA profile element in the ML IE).

-> This field may also be used when the AP advertises CSN information onAPs (including the reporting AP and the reported AP) through thebeacon/probe response. This field is not necessary when the changesequence element is used to advertise the CSN information, but the ‘CSNpresence’ (sub)field indicating a presence of the field is necessarywhen the change sequence field is used. In this case, the (sub)field maybe included variously according to a location at which CSN informationof each AP is included. It may be included in the beacon/probe responseframe (e.g., when CSN information on the reporting AP is located in thebeacon/probe response frame), or may be included in a common info partin the ML IE (e.g., when the CSN information on the reported AP islocated in the common info part in the ML IE), or may be included in aper-STA profile (when the CSN information on the reported AP is locatedin a link info part in the ML IE).

In this case, if the non-AP STA requests critical update information onthe STA (x) by setting a value of the ‘critical update request’ field ofthe per-STA control in the per-STA profile (x) of the multi-link element(e.g., probe request variant multi-link element) to 1 in order torequest critical update information on each of STA (x), (y), . . .(i.e., AP (x), (y), . . . ) by using the MLD probe request, an AP whichhas received this may respond as follows for an MLD probe response.

1) When the non-AP STA transmits the MLD probe request including CSNinformation thereof (i.e., it may be included in the form of the changesequence element or the change sequence field as CSN informationreceived most recently) in the per-STA profile (x), together with‘critical update request’ field=1′.

A. The AP may compare the CSN information on the non-AP STA (x) with thecurrent CSN information on the AP (x) connected to the non-AP STA (x),and may make a response by including only updated critical updateinformation (i.e., elements classified as an critical update event inthe 802.11be) in the MLD probe response.

B. In this case, however, if the receiving AP MLD does not implement afunction of tracking update information for each CSN of the AP, it isnot possible to know which information is updated for each CSN version.Therefore, a response may be made by including all current criticalupdate information on the AP (x) connected to the non-AP STA (x) (i.e.,elements classified as the critical update event in the 802.11be) in theMLD probe response.

C. Although it is proposed in the present specification that a responseis made for all current critical update information on the AP (x), notcomplete information on the AP (x), in order to reduce an overhead ofthe MLD probe response, it is also possible to respond with a completeprofile (i.e., complete information) of the AP (x) even if the MLD proberequest which is set to ‘Critical update request’ field=1 in the per-STAprofile (x) is received from the non-AP STA according to an APimplementation.

2) When the non-AP STA transmits the MLD probe request by omitting CSNinformation thereof (i.e., CSN information received most recently) inthe per-STA profile (x), together with ‘Critical update request’field=1.

A. Since the AP does not know CSN information on the non-AP STA (x), aresponse may be made by including all current critical updateinformation on the AP (x) connected to the non-AP STA (x) (i.e.,elements classified as the critical update event in the 802.11be) in theMLD probe response.

B. Although it is proposed in the present specification that a responseis made for all current critical update information on the AP (x), notcomplete information on the AP (x), in order to reduce an overhead ofthe MLD probe response, it is also possible to respond with a completeprofile (i.e., complete information) of the AP (x) even if the MLD proberequest which is set to ‘Critical update request’ field=1 in the per-STAprofile (x) is received from the non-AP STA according to an APimplementation.

FIG. 52 illustrates an example of an MLD probe request which uses achange sequence element when critical update information is requested.

FIG. 53 illustrates another example of an MLD probe request which uses achange sequence element when critical update information is requested.

For example, when a non-AP STA requests critical update information on aspecific STA (x), it may be set as shown in FIG. 53 that critical updaterequest=1, and change sequence number information (e.g., change sequenceelement or change sequence field) may be transmitted together. In thiscase, the non-AP STA may optionally omit the change sequence numberinformation in transmission. In this case, however, there may be alimitation in information to be included in the MLD probe response withwhich an AP responds as defined above.

FIG. 54 illustrates an example in which a critical update request fieldis included in an ML IE format.

Referring to FIG. 54 , when a critical update request field is locatedin an ML IE as described above, critical update information on all linksindicated through a per-STA profile (x) may be requested. If thecritical update request field is included at a location where commoninformation is included in the ML IE, and if a field value is indicatedwith 1 in transmission, an AP which has received this responds with aresponse frame including critical update information on links requestedin a corresponding request frame. Alternatively, the critical updaterequest field may be indicated by being included in a subfield in themulti-link control field in the ML IE. A form of a field defined as such(field or subfield or sub-element, etc.) or a location in the ML IE maybe defined variously according to a definition in a standard.

Second, there is a method of using a change sequence element for acritical update information request of other APs. In the 802.11ah, whenthe probe request frame is transmitted by including the change sequenceelement, the AP transmits the compressed probe response frame includingonly changed critical update information on a corresponding link in theprobe response frame. This may also be utilized in the 802.11be.

When an STA makes a request by including a change sequence element inthe probe response frame together with a link indicator for other APs,an AP which has received this transmits a probe response including onlychanged critical update information on indicated links in the proberesponse. The change sequence element may be included in any element orsub-element in the request frame, and may also be used by being includedin the MLD request element or the ML IE. An embodiment thereof is asshown in FIG. 55 .

FIG. 55 illustrates an example in which a change sequence element isincluded in an ML IE format.

For example, when a change sequence element is included in an ML IE intransmission as shown in FIG. 55 , an AP compares a change sequencefield value currently owned by the AP for links indicated through the MLIE and a change sequence field value in a change sequence elementtransmitted by an STA, and when there is a change, makes a response byincluding changed critical update information in a probe response. Inthis case, the change sequence element transmitted by the STA shallinclude change sequence information on all links for which informationis requested in the ML IE. Therefore, when the existing change sequenceelement is used, link indicator information additionally requested maybe necessary. Additionally, the present specification also considers anoption in which transmission is performed by including all informationrelated to the critical update, currently owned by the AP, when thechange sequence element is included in the ML IE in transmission asdescribed above. If the change sequence field value transmitted by theSTA and the field currently owned by the AP are different as a result ofcompassion performed by the AP, all information related to the criticalupdate, currently owned by the AP, is transmitted to the STA. Thismethod may result in an increase in an overhead for informationtransmitted by the AP, but may be implemented more simply since there isno need to store change information for each critical update version foreach AP.

In addition, the present specification additionally proposes a newelement considering an MLD.

‘MLD Change Sequence element’: An element which may include changesequence information on several links

An embodiment thereof is as shown in FIG. 56 and FIG. 57 .

FIG. 56 illustrates an example of an MLD change sequence format.

FIG. 57 illustrates another example of an MLD change sequence format.

An MLD change sequence value may be represented by repeatedly arranginga per-link change sequence value as shown in FIG. 56 , or may berepresented by indicating each of link ID information and changesequence information after indicating the number of links with ‘Thenumber of link ID’ as shown in FIG. 57 .

An embodiment for the MLD change sequence element is as shown in FIG. 58.

FIG. 58 illustrates an example of an MLD change sequence element.

When an MLD change sequence element is transmitted by being included inan ML IE in a probe request frame as shown in FIG. 58 , an AP maycompare a change sequence value received for each link and a changesequence value owned by the AP, and may make a response by includingchanged critical update information on links corresponding to an updatedchange sequence value in a response frame. In this case, if an STA hasno request for different information for each link, a per-STA profile(x) sub-element may be omitted in transmission.

In this case, when the existing change sequence element is used, it maybe used as shown in FIG. 59 .

FIG. 59 illustrates an example of a change sequence element in theconventional standard.

The existing change sequence element in an ML IE may be directly used torequest critical update information updated for each link. An embodimentthereof may be as shown in FIG. 59 .

FIG. 60 illustrates another example in which a change sequence elementis included in an ML IE format.

Referring to FIG. 60 , when an STA transmits a probe request including achange sequence element in a per-STA profile (x) in an ML IE, it means achanged critical update information request of a link indicated in theper-STA profile (x). Accordingly, an AP which has verified the changesequence element included in the request frame may compare a receivedchange sequence value and a change sequence value owned by the AP, andif there is an update (i.e., if there is changed information to beupdated by the STA), may transmit the response frame including changedcritical update information or may transmit the response frame includingcomplete critical update-related information.

Third, there is a method in which a change sequence field is usedtogether with the ‘critical update request’ field defined above for arequest for critical update information on other APs. The ‘criticalupdate request’ field is defined as follows as an indicator forrequesting information on other APs by an STA.

-   -   ‘Critical update request’ field: a field which requests only        system information defined as critical update of an AP. It may        be used together with a link indicator and may be used when        system information defined as critical update of a specific link        is requested.

However, in a case where the STA requests critical update information ona specific link by using a 1-bit indicator as described above, when anAP which has received this does not know a version of critical updateinformation currently owned by the STA (i.e., a change sequence fieldvalue of critical update information currently owned by the STA), the APshall transmit a response message including all critical updateinformation on a requested link. In addition, the response frame mayalso be transmitted by including the change sequence element togetherwith the critical update information. Although this is a simple method,information which is already owned by the STA may be transmittedredundantly. Therefore, a format for reducing an overhead thereof isadditionally proposed. An embodiment thereof is as follows.

FIG. 61 illustrates an example of a probe request frame for a criticalupdate information request.

Referring to FIG. 61 , an STA may transmit a request frame includingchange sequence fields (or change sequence element) indicating versioninformation of critical update, currently owned by the STA, togetherwith a critical update request frame which is an indicator forindicating a critical update information request. In this case, thechange sequence fields mean an indicator indicating a per-link changesequence value. In the 802.11be, the STA may periodically receive achange sequence value for APs of a connected AP MLD through a beacon ora probe request. In addition, since it is defined that the STA storesthese values, the STA knows per-link change sequence value informationcurrently received by the STA. Therefore, the change sequence fieldsdefined in the present specification mean information on versions (i.e.,change sequence values) of critical update information on the APs of theconnected AP MLD, which is obtained previously by the STA through thebeacon or the probe response.

In this case, when a value of the ‘critical update request’ field is 1,it means that the STA requests critical update information, andotherwise, this value is indicated with 0. When the value of the‘critical update request’ field is 0, since it means a critical updateinformation request, transmission is performed by including the changesequence fields (or change sequence elements), whereas when the value is0, this field is omitted in transmission. That is, in other words, whenthe value of the ‘critical update request’ field is 1, since the STAperforms transmission by adding the changed sequence fields (or changesequence elements), an AP which has received this may transmit aresponse message by inserting only changed information (i.e., onlychanged information to be updated by the STA) as a result of comparingwith information currently owned by the AP, and when the value of the‘critical update request’ field is 0, the change sequence fields (orchange sequence elements) are omitted in transmission to reduce anoverhead. Additionally, the present specification also considers anoption in which transmission is performed by including all informationrelated to the critical update, currently owned by the AP, when thechange sequence element is included in the ML IE in transmission asdescribed above. If the change sequence field value transmitted by theSTA and the field currently owned by the AP are different as a result ofcompassion performed by the AP, all information related to the criticalupdate, currently owned by the AP, is transmitted to the STA. Thismethod may result in an increase in an overhead for informationtransmitted by the AP, but may be implemented more simply since there isno need to store change information for each critical update version foreach AP.

As such, the change sequence field (or change sequence element) may bedefined by identifying a presence/absence thereof according to the‘critical update request’ field value. Optionally, however, the‘critical update request’ field value and the change sequence field (orchange sequence element) may be used by being defined independently. Ifa request message transmitted by the STA does not include the changesequence fields (or change sequence elements) together with the‘critical update request’ field having a value of 1, it is regarded thatan AP which has received this desires to receive all critical updateinformation, not the updated crucial update information alone, and thusa response is made by including all crucial update information in aresponse message. The present specification proposes a method in whichchange sequence value information obtained previously by the STA istransmitted together with the ‘critical update request’ field, and iscompared with change sequence value information currently owned by theAP, and only changed information is transmitted by being inserted to aresponse frame as described below. In this case, although the changesequence fields are provided in this section as an example oftransferring change sequence information on a link, the STA may requestwith the change sequence elements, not the change sequence fields.However, since the use of the change sequence element is alreadymentioned in the section above, an embodiment in which the changesequence element is used together with the ‘critical update request’field is omitted in this section.

For example, when the STA transmits the probe request frame includingthe ML IE for MLD probing, information for requesting critical updatemay be included in a per-STA profile (x) sub-element for requestinginformation for each STA as shown in FIG. 61 . In this case, thecritical update request field is included in the per-STA control field,and the change sequence fields having the current critical updateinformation of the STA may be located in the per-STA profile (x). Inthis case, the critical update sequence field may be located togetherwith the change sequence fields in the per-STA profile (x), not in theper-STA control field. An embodiment thereof is as shown in FIG. 62 .

FIG. 62 illustrates another example of a probe request frame for acritical update information request.

An AP which has received a request frame of FIG. 62 identifies ML IEinformation in the request frame, and transmits a response messageincluding critical update information on a specific link, requested byan STA. In this case, if the critical update request field is present inthe per-STA profile (x) in the ML IE and if a value thereof is 1, it isrecognized that the critical update information is requested by the STA.In addition, change sequence information owned by the STA may becompared with current change sequence information on a link (X)requested by the STA through the change sequence fields informationreceived together in this case, and if there is an update (i.e., ifthere is changed information to be updated by the STA), a compressedprobe response frame including only updated information may betransmitted, or if there is an update, a response may be made for allinformation related to critical update by using a probe response frame.

Information mentioned above may be included not in a link-specific levelin the ML IE but in a common info level, and thus critical updateinformation may be requested not for a specific link but for all linksat a time.

An embodiment thereof is as shown in FIG. 63 .

FIG. 63 illustrates another example of a probe request frame for acritical update information request.

As shown in FIG. 63 , an STA may transmit a request frame including acritical update request field (i.e., a value is set to 1) and changessequence fields at a common information location, not in a link-specificinformation location (e.g., per-STA profile (x)) in an ML IE. An APwhich has received this may recognize that it is a request for all linksowned by the STA, not for a specific link, and may compare changesequence fields information transmitted by the STA and current changesequence information on all links owned by the AP, and if there is anupdate (i.e., if there is changed information to be updated by the STA),a compressed probe response frame including only updated information onall links may be transmitted, or if there is an update, a response maybe made for all information related to critical update by using a proberesponse frame.

FIG. 64 illustrates another example of a probe request frame for acritical update information request.

In this case, a critical update request field is located in themulti-link control field as shown in FIG. 64 , and the STA may alsoindicate a changed critical update information request of a link.

Regarding the aforementioned method in which the STA requests criticalupdate change information on a specific AP, the present specificationadditionally proposes a response operation in which an AP responds. Inthe current 802.11ax standard, when a 6 GHz AP receives a probe request,if the AP does not indicate an actual SSID of an SSID element of abeacon frame of the AP in transmission of a probe response frame, a ruleof transmitting it by setting a broadcast address in an address 1 fieldis pre-defined. In a method being discussed in the 802.1be standard withreference to this, an address 1 field is set to a broadcast address ifthe AP does not indicate the actual SSID of the SSID element of thebeacon frame of the AP when responding with an MLD probe response frame,in case of receiving an MLD probe request frame for requesting completeinformation on the AP operating at a 2.4 GHz band or a 5 GHz band.

For this, the present specification proposes a method in which theaddress 1 field is set to the broadcast address if the AP does notindicate the actual SSID of the SSID element of the beacon frame of theAP when the AP responds with the MLD probe response frame, even in acase where the STA requests critical update related information on aspecific AP through the MLD probe request frame (e.g., when the STAtransmits the MLD probe request frame including the change sequencefield information). The critical update information is critical changeinformation on the AP, which shall be known to all STAs before datatransmission/reception. Therefore, in order to avoid a storm caused byMLD probing, the present specification proposes a method of respondingwith a broadcast message in the absence of an additional indicator whenthe STA requests partial information on critical update of a specificAP.

In addition, as described above, a method in which the AP MLD storeswhich information (i.e., IEs) is updated for each change sequence number(CSN) of each AP (whenever critical update occurs) may be implementedaccording to an implementation of the AP MLD, or may not be implementedaccording to a memory size. If the method is supported, the AP needs toremember specific IE information for which update occurs whenever theCSN of the AP changes. For example, when a critical update event for anelement X occurs at CSN n=1 and when an update for elements Y and Zoccurs at CSN=n+1, the AP shall maintain information indicating whichinformation is changed at CSN=n and CSN n+1. As such, if the AP iscapable of tracking which IE changes for each CSN, when the STAtransmits a request frame including CSN information currently stored inthe STA, not complete information but only changed information may beincluded in transmission by comparing with the current CSN value of theAP, which may be useful in terms of an overhead. However, the trackingmay not be easy, and a corresponding ability may be supported or may notbe supported according to an implementation of the AP since anadditional memory may also be required for the AP. Therefore, an abilityfor indicating the capacity for tracking the per-CSN update informationon the AP is proposed in the disclosure as follows.

-   -   ‘Critical update Tracking Support’ field: This field is        information used by the STA or AP to indicate whether to support        a function of storing which information (e.g., element ID (EI)        information) is updated currently for each CSN value. When a        value thereof is 1, this means that the STA or the AP supports        an ability for storing specific information for which update        occurs for each CSN value, and when the value is 0, it means        that the STA or the AP does not support this ability. For        example, this field may be included in an extended capabilities        element, an EHT capabilities element, or the like.

The STA may verity whether a corresponding AP (or STA) supports thisfunction in an association process, and may utilize this to requestcritical update information on a specific AP (or STA). This function maybe supported at an MLD level, or may be supported at an STA level foreach STA.

As such, when the ‘critical update tracking support’ field indicatingwhether to support critical update tracking of the MLD is defined, aspecific operation based on this may be defined as follows.

For example, when the AP MLD supports critical update tracking (e.g.,‘Critical update Tracking Support’ field=1), the non-AP MLD may knowthis in a multi-link setup process.

When the AP MLD supports the critical update tracking, the STA of thenon-AP MLD may transmit a probe request frame including change sequencenumber (CSN) information when only partial information related tocritical update is requested. An AP which has received this may comparethe current CAN of the AP and the CSN information received from the STA,and may transmit a probe response frame including only updatedinformation. In this case, however, when the STA desires to obtain notonly changed information but also complete information related tocritical update of the AP, desired information (complete informationrelated to critical update of the AP) may be obtained by transmittingthe probe request frame not including the CSN information when thepartial information related to critical update is requested.

When the AP MLD does not support the critical update tracking (e.g.,‘Critical update Tracking Support’ field=0), the STA of the non-AP MLDmay not transmit the probe request frame including the CSN informationwhen only information related to critical update is requested. An APwhich has received this may transmit the probe response frame includingelement information related to all critical updates corresponding to thecurrent CSN of the AP (or if there is no additional instruction,requested complete information (i.e., complete profile) of the AP. Inthis case, however, the STA may transmit the probe request frameincluding the CSN information when partial information related tocritical update is requested. However, since the AP which has receivedthis is not able to track update information for each CSN, the proberesponse frame including element information related to all criticalupdates corresponding to the current CAN of the AP (or if there is noadditional instruction, requested complete information (i.e., completeprofile) of the AP) may be transmitted.

As such, if the non-AP MLD may know whether to support tracking ofper-CSN update information on the AP MLD by defining the ‘criticalupdate tracking support’ field in the MLD, it may be useful since thenon-AP MLD may determine whether to include CSN information in the proberequest frame when partial information related to critical update isrequested.

According to an embodiment, the AP MLD and the non-AP MLD may enable anIOM method proposed through the signaling method proposed in the presentspecification in the process or the multi-link setup or after themulti-link setup. In addition, the AP MLD and the non-AP MLD mayrestrict an information range and type requested through various fieldvalues in an IOM capability element.

According to an embodiment, although an IOM operation may be performedafter accurate operational negotiation between the MLDs through theaforementioned signaling method, the IOM operation may also be performedby implementation of the MLD without an additional signaling process.This may imply that the operation is performed by implementing the APMLD or the non-AP MLD, without negotiation of the AP MLD and the non-APMLD.

The AP MLD and the non-AP MLD may operate, based on the aforementionedembodiments. However, when the MLD performs the IOM operation withoutadditional signal exchange, the following restriction may occur.

1) Restriction on the solicited method: If info sharing is not supportedbetween the APs of the AP MLD, a response may be made when the STArequests information on another link.

2) Restriction on the unsolicited method: The AP may provide anadditional message (e.g., beacon period, etc.) by autonomouslydetermining an STA which requires additional link information.Therefore, the STA may not predict whether the STA will receive thisinformation.

When the MLD implements the IOM without an additional signal method,advantageously, an operation process becomes simple, but there is aproblem in that the aforementioned restrictions may occur.

According to an embodiment, a method of requesting information on amulti-link may be configured based on the agreement between the AP MLDand the non-AP MLD, performed by using the aforementioned IOM capabilityelement. Unlike this, in case of the solicited method, the STA mayindicate specific information, not agreed content, and may desire totemporarily obtain the information. In this case, when the STAdynamically transmits a request message, a request may be made byincluding indicated content (e.g., IOM capability information).

For example, although the STA may receive information provided by theAP, based on the content agreed between the AP MLD and the non-AP MLD inthe process or after the multi-link setup, the STA may desire totemporarily request information on a specific AP or specific parameterinformation on APs. In this case, when information is requested, the STAmay transmit a request frame (e.g., probe request frame, (re)associationframe, new frame, etc.) including an instruction for information desiredto be requested in the “IOM capability” element. The AP maytransmit/provide to the STA a response message including informationdesired to be requested by the STA. According to an embodiment, when afield in the IOM capability element is omitted, the AP may provideinformation to the STA, based on the existing negotiated content.

Accordingly, the MLD (AP MLD or non-AP MLD) may perform negotiationbetween the AP MLD and the non-AP MLD by using the aforementionedelement, in the process or after the multi-link setup. The non-AP MLDmay agree on information to be provided (or information to be received),based on the negotiation, and may receive the agreement. In addition,the STA may transmit a request message including an instruction oninformation described to be received, so that only requested informationis temporarily received. However, when a specific instruction is omittedin the request message, the non-AP MLD and the AP MLD may operate basedon an instruction agreed by default.

According to an embodiment, when it is desired to change the agreedcontent after the multi-link setup is complete, the non-AP MLD and theAP MLD may update the content agreed between the MLDs through additionalmessage exchange.

A procedure for BSS parameter critical update will be described asfollows.

When an AP of an AP MLD does not belong to a multi-BSSID or if the APcorresponds to a transmitted BSSID in a multi-BSSID set, the APtransmits a beacon and a probe response frame including a BSS parameterchange count (BPCC) subfield for each of all APs belonging to the sameAP MLD.

A value of the BPCC subfield of each AP is initialized to 0, and shallbe incremented (module 256) when critical update occurs for anoperational parameter for the AP.

The BPCC subfield for each of other APs of the AP MLD shall betransferred in an MLD parameters subfield of a target beacontransmission time (TBTT) information field of a reduced neighbor report(RNR) element corresponding to the AP.

The BPCC subfield for the AP shall be transferred in the common infofield of the basic multi-link element.

The AP provides a critical update flag subfield of a capabilityinformation field of a beacon and probe response frame, and transmits anupdate indicator for a value transferred in the BPCC subfield of the MLDparameters field of the RNR element of a specific AP of the same AP MLD(or a value transferred in the BPCC subfield of the common info field ofthe basic multi-link element).

When there is a change in a value transferred in a BPCC subfield of theMLD parameters field of the RNR element for a specific AP of the same APMLD (or a value transferred in a BPCC subfield of a common info field ofthe basic multi-link element), the AP sets the critical update flagsubfield of the capability information field in the beacon frame to 1,and allows to include a next DTIM beacon frame for a link in which theAP operates.

Otherwise, the AP sets the critical update frag subfield of thecapability information field to 1.

The non-AP MLD shall maintain a record of a value of the most recentlyreceived BPCC subfield for each AP of the AP MLD in which a multi-linkis configured.

Hereinafter, the aforementioned embodiment will be described withreference to FIG. 1 to FIG. 64 .

FIG. 65 is a flowchart illustrating a procedure in which a transmittingMLD provides a receiving MLD with complete or partial information on anAP, based on a probe response frame according to the present disclosure.

An example of FIG. 65 may be performed in a network environment in whicha next-generation WLAN system (IEEE 802.11be or EHT WLAN system) issupported. The next-generation WLAN system is a WLAN system evolved froman 802.11ax system, and may satisfy backward compatibility with the802.11ax system.

The present embodiment proposes a method and apparatus in which, when anon-AP STA requests information on not a peer AP but other APs through aprobe request frame, the probe request frame includes a completeinformation profile subfield, so that whether the request is a partialinformation request or a complete information request is determinedaccording to a value of the complete information profile subfield.Herein, a transmitting MLD may correspond to an AP MLD, and a receivingMLD may correspond to a non-AP MLD. If the non-AP STA is a firstreceiving STA, a first transmitting STA connected to the first receivingSTA through a first link may be a peer AP, and second and thirdtransmitting STAs connected through other links may be other APs.

In operation S6510, the transmitting MLD receives a probe request framefrom a receiving MLD through a first link.

In step S6520, the transmitting MLD transmits a probe response frame tothe receiving MLD through the first link.

The transmitting MLD includes a first transmitting station (STA)operating in the first link and a second transmitting STA operating in asecond link. The receiving MLD includes a first receiving STA operatingin the first link and a second receiving STA operating in the secondlink.

The probe request frame includes a profile field of the second receivingSTA. The profile field of the second receiving STA includes a firstcomplete information profile subfield.

When the first receiving STA requests partial information on the secondlink, a value of the first complete information profile subfield is setto 0. When the first receiving STA requests complete information on thesecond link, the value of the first complete information profilesubfield is set to 1.

That is, the probe response frame may be configured based on the valueof the first complete information profile subfield. When the value ofthe first complete information profile subfield is 0, the transmittingMLD may transfer the probe response frame including the partialinformation the second link. When the value of the first completeinformation profile subfield is 1, the transmitting MLD may transfer theprobe response frame including the complete information on the secondlink.

In addition, the receiving MLD may request complete information orpartial information on a plurality of APs in the transmitting MLD.

The transmitting MLD further may include a third transmitting STAoperating in a third link. The receiving MLD further may include a thirdreceiving STA operating in the third link.

The probe request frame may further include a profile field of the thirdreceiving STA. A profile field of the third receiving STA may include asecond complete information profile subfield.

When the first receiving STA requests partial information on the thirdlink, a value of the second complete information profile subfield may beset to 0. When the first receiving STA requests complete information onthe third link, a value of the third complete information profilesubfield may be set to 1.

Likewise, the probe response frame may be configured based on the valueof the second complete information profile subfield. When the value ofthe second complete information profile subfield is 0, the transmittingMLD may transfer the probe response frame including the partialinformation the third link. When the value of the second completeinformation profile subfield is 1, the transmitting MLD may transfer theprobe response frame including the complete information on the thirdlink.

That is, the present embodiment proposes a method of identifying whethera non-AP STA (first receiving STA) requests complete information onother APs (second and third transmitting STAs) in an AP MLD or requestspartial information thereof through the aforementioned completeinformation profile subfield. Accordingly, the AP MLD may decode thecomplete information profile subfield to determine whether to includecomplete information on other APs in a probe response frame or toinclude partial information therein.

The probe request frame may include a first request element and amulti-link element. When the first receiving STA requests partialinformation on the first link, the partial information on the first linkmay be requested based on the first request element. The profile fieldsof the second and third receiving STAs may be included in the multi-linkelement. That is, in MLD communication, the non-AP STA may requestinformation on a peer AP through a request element not included in themulti-link element, and may request information on another AP which isnot the peer AP through the multi-link element.

The profile field of the second receiving STA may further include afirst update subfield.

When a value of the first update subfield is set to 1, the proberesponse frame may include only updated information out of the requestedpartial information on the second link. When the value of the firstupdate subfield is set to 0, the probe response frame may include therequested partial information on the second link.

The profile field of the third receiving STA may further include asecond update subfield. When a value of the second update subfield isset to 1, the probe response frame may include only updated informationout of the requested partial information on the third link. When thevalue of the second update subfield is set to 0, the probe responseframe may include the requested partial information on the third link.

FIG. 66 is a flowchart illustrating a procedure in which a receiving MLDprovides a transmitting MLD with complete or partial information on anAP, based on a probe request frame according to the present disclosure.

An example of FIG. 66 may be performed in a network environment in whicha next-generation WLAN system (IEEE 802.11be or EHT WLAN system) issupported. The next-generation WLAN system is a WLAN system evolved froman 802.11ax system, and may satisfy backward compatibility with the802.11ax system.

The present embodiment proposes a method and apparatus in which, when anon-AP STA requests information on not a peer AP but other APs through aprobe request frame, the probe request frame includes a completeinformation profile subfield, so that whether the request is a partialinformation request or a complete information request is determinedaccording to a value of the complete information profile subfield.Herein, a transmitting MLD may correspond to an AP MLD, and a receivingMLD may correspond to a non-AP MLD. If the non-AP STA is a firstreceiving STA, a first transmitting STA connected to the first receivingSTA through a first link may be a peer AP, and second and thirdtransmitting STAs connected through other links may be other APs.

In operation S6610, a receiving MLD transmits a probe request frame to atransmitting MLD through a first link.

In step S6620, the receiving MLD receives a probe response frame fromthe transmitting MLD through the first link.

The transmitting MLD includes a first transmitting station (STA)operating in the first link and a second transmitting STA operating in asecond link. The receiving MLD includes a first receiving STA operatingin the first link and a second receiving STA operating in the secondlink.

The probe request frame includes a profile field of the second receivingSTA. The profile field of the second receiving STA includes a firstcomplete information profile subfield.

When the first receiving STA requests partial information on the secondlink, a value of the first complete information profile subfield is setto 0. When the first receiving STA requests complete information on thesecond link, the value of the first complete information profilesubfield is set to 1.

That is, the probe response frame may be configured based on the valueof the first complete information profile subfield. When the value ofthe first complete information profile subfield is 0, the transmittingMLD may transfer the probe response frame including the partialinformation the second link. When the value of the first completeinformation profile subfield is 1, the transmitting MLD may transfer theprobe response frame including the complete information on the secondlink.

In addition, the receiving MLD may request complete information orpartial information on a plurality of APs in the transmitting MLD.

The transmitting MLD further may include a third transmitting STAoperating in a third link. The receiving MLD further may include a thirdreceiving STA operating in the third link.

The probe request frame may further include a profile field of the thirdreceiving STA. A profile field of the third receiving STA may include asecond complete information profile subfield.

When the first receiving STA requests partial information on the thirdlink, a value of the second complete information profile subfield may beset to 0. When the first receiving STA requests complete information onthe third link, a value of the third complete information profilesubfield may be set to 1.

Likewise, the probe response frame may be configured based on the valueof the second complete information profile subfield. When the value ofthe second complete information profile subfield is 0, the transmittingMLD may transfer the probe response frame including the partialinformation the third link. When the value of the second completeinformation profile subfield is 1, the transmitting MLD may transfer theprobe response frame including the complete information on the thirdlink.

That is, the present embodiment proposes a method of identifying whethera non-AP STA (first receiving STA) requests complete information onother APs (second and third transmitting STAs) in an AP MLD or requestspartial information thereof through the aforementioned completeinformation profile subfield. Accordingly, the AP MLD may decode thecomplete information profile subfield to determine whether to includecomplete information on other APs in a probe response frame or toinclude partial information therein.

The probe request frame may include a first request element and amulti-link element. When the first receiving STA requests partialinformation on the first link, the partial information on the first linkmay be requested based on the first request element. The profile fieldsof the second and third receiving STAs may be included in the multi-linkelement. That is, in MLD communication, the non-AP STA may requestinformation on a peer AP through a request element not included in themulti-link element, and may request information on another AP which isnot the peer AP through the multi-link element.

The profile field of the second receiving STA may further include afirst update subfield. When a value of the first update subfield is setto 1, the probe response frame may include only updated information outof the requested partial information on the second link. When the valueof the first update subfield is set to 0, the probe response frame mayinclude the requested partial information on the second link.

The profile field of the third receiving STA may further include asecond update subfield. When a value of the second update subfield isset to 1, the probe response frame may include only updated informationout of the requested partial information on the third link. When thevalue of the second update subfield is set to 0, the probe responseframe may include the requested partial information on the third link.

The aforementioned technical feature of the present specification may beapplied to various apparatuses and methods. For example, theaforementioned technical feature of the present specification may beperformed/supported through the apparatus of FIG. 1 and/or FIG. 11 . Forexample, the aforementioned technical feature of the presentspecification may be applied only to part of FIG. 1 and/or FIG. 11 . Forexample, the aforementioned technical feature of the presentspecification may be implemented based on the processing chips 114 and124 of FIG. 1 , or may be implemented based on the processors 111 and121 and memories 112 and 122 of FIG. 1 , or may be implemented based onthe processor 610 and memory 620 of FIG. 11 . For example, the apparatusof the present specification transmits a probe request frame to atransmitting MLD through a first link, and receives a probe responseframe from the transmitting MLD through the first link.

The technical feature of the present specification may be implementedbased on a computer readable medium (CRM). For example, the CRM proposedby the present specification is at least one computer readable mediumincluding an instruction executed by at least one processor.

The CRM may store instructions executing operations including:transmitting a probe request frame to a transmitting MLD through a firstlink; and receiving a probe response frame from the transmitting MLDthrough the first link. The instruction stored in the CRM of the presentspecification may be executed by at least one processor. The at leastone processor related to the CRM of the present specification may be theprocessors 111 and 121 or processing chips 114 and 124 of FIG. 1 or theprocessor 610 of FIG. 11 . Meanwhile, the CRM of the presentspecification may be the memories 112 and 122 of FIG. 1 or the memory620 of FIG. 11 or a separate external memory/storage medium/disk or thelike.

The foregoing technical features of the present specification areapplicable to various applications or business models. For example, theforegoing technical features may be applied for wireless communicationof a device supporting artificial intelligence (AI).

Artificial intelligence refers to a field of study on artificialintelligence or methodologies for creating artificial intelligence, andmachine learning refers to a field of study on methodologies fordefining and solving various issues in the area of artificialintelligence. Machine learning is also defined as an algorithm forimproving the performance of an operation through steady experiences ofthe operation.

An artificial neural network (ANN) is a model used in machine learningand may refer to an overall problem-solving model that includesartificial neurons (nodes) forming a network by combining synapses. Theartificial neural network may be defined by a pattern of connectionbetween neurons of different layers, a learning process of updating amodel parameter, and an activation function generating an output value.

The artificial neural network may include an input layer, an outputlayer, and optionally one or more hidden layers. Each layer includes oneor more neurons, and the artificial neural network may include synapsesthat connect neurons. In the artificial neural network, each neuron mayoutput a function value of an activation function of input signals inputthrough a synapse, weights, and deviations.

A model parameter refers to a parameter determined through learning andincludes a weight of synapse connection and a deviation of a neuron. Ahyper-parameter refers to a parameter to be set before learning in amachine learning algorithm and includes a learning rate, the number ofiterations, a mini-batch size, and an initialization function.

Learning an artificial neural network may be intended to determine amodel parameter for minimizing a loss function. The loss function may beused as an index for determining an optimal model parameter in a processof learning the artificial neural network.

Machine learning may be classified into supervised learning,unsupervised learning, and reinforcement learning.

Supervised learning refers to a method of training an artificial neuralnetwork with a label given for training data, wherein the label mayindicate a correct answer (or result value) that the artificial neuralnetwork needs to infer when the training data is input to the artificialneural network. Unsupervised learning may refer to a method of trainingan artificial neural network without a label given for training data.Reinforcement learning may refer to a training method for training anagent defined in an environment to choose an action or a sequence ofactions to maximize a cumulative reward in each state.

Machine learning implemented with a deep neural network (DNN) includinga plurality of hidden layers among artificial neural networks isreferred to as deep learning, and deep learning is part of machinelearning. Hereinafter, machine learning is construed as including deeplearning.

The foregoing technical features may be applied to wirelesscommunication of a robot.

Robots may refer to machinery that automatically process or operate agiven task with own ability thereof. In particular, a robot having afunction of recognizing an environment and autonomously making ajudgment to perform an operation may be referred to as an intelligentrobot.

Robots may be classified into industrial, medical, household, militaryrobots and the like according uses or fields. A robot may include anactuator or a driver including a motor to perform various physicaloperations, such as moving a robot joint. In addition, a movable robotmay include a wheel, a brake, a propeller, and the like in a driver torun on the ground or fly in the air through the driver.

The foregoing technical features may be applied to a device supportingextended reality.

Extended reality collectively refers to virtual reality (VR), augmentedreality (AR), and mixed reality (MR). VR technology is a computergraphic technology of providing a real-world object and background onlyin a CG image, AR technology is a computer graphic technology ofproviding a virtual CG image on a real object image, and MR technologyis a computer graphic technology of providing virtual objects mixed andcombined with the real world.

MR technology is similar to AR technology in that a real object and avirtual object are displayed together. However, a virtual object is usedas a supplement to a real object in AR technology, whereas a virtualobject and a real object are used as equal statuses in MR technology.

XR technology may be applied to a head-mount display (HMD), a head-updisplay (HUD), a mobile phone, a tablet PC, a laptop computer, a desktopcomputer, a TV, digital signage, and the like. A device to which XRtechnology is applied may be referred to as an XR device.

The claims recited in the present specification may be combined in avariety of ways. For example, the technical features of the methodclaims of the present specification may be combined to be implemented asa device, and the technical features of the device claims of the presentspecification may be combined to be implemented by a method. Inaddition, the technical characteristics of the method claim of thepresent specification and the technical characteristics of the deviceclaim may be combined to be implemented as a device, and the technicalcharacteristics of the method claim of the present specification and thetechnical characteristics of the device claim may be combined to beimplemented by a method.

What is claimed is:
 1. A method in a wireless local area network (WLAN)system, the method comprising: transmitting, by a first non-access point(AP) station (STA), a multi-link probe request frame to a first AP; andreceiving, by the first non-AP STA, a multi-link probe response framefrom the first AP, wherein the first AP operating on a first link and asecond AP operating on a second link are affiliated with an APmulti-link device (MLD), wherein the first non-AP STA operating on thefirst link and a second non-AP STA operating on the second linkaffiliated with a non-AP MLD, wherein the multi-link probe request frameincludes a profile field for the second AP, wherein the profile fieldfor the second AP includes a first Complete Profile Requested subfieldof a first STA Control field, wherein based on the first non-AP STArequesting partial information on the second AP, a value of the firstComplete Profile Requested subfield is set to 0, and wherein based onthe first non-AP STA requesting complete information on the second AP,the value of the first Complete Profile Requested subfield is set to 1.2. The method of claim 1, wherein a third AP operating on a third linkis further affiliated with the AP MLD, wherein a third non-AP STAoperating on the third link is further affiliated with the non-AP MLD,wherein the multi-link probe request frame further includes a profilefield for the third AP, wherein the profile field for the third APincludes a second Complete Profile Requested subfield of a second STAControl field.
 3. The method of claim 2, wherein based on the firstnon-AP STA requesting partial information on the third AP, a value ofthe second Complete Profile Requested subfield is set to 0, and whereinbased on the first non-AP STA requesting complete information on thethird AP, a value of the second Complete Profile Requested subfield isset to
 1. 4. The method of claim 1, wherein the probe request frameincludes a first request element and a multi-link element, wherein basedon the first non-AP STA requesting partial information on the first AP,partial information on the first AP is requested based on the firstrequest element, and wherein the profile fields for the second and thirdAPs are included in the multi-link element.
 5. The method of claim 1,wherein the profile field for the second AP further includes a firstupdate subfield, wherein based on a value of the first update subfieldbeing set to 1, the multi-link probe response frame includes onlyupdated information out of the requested partial information on thesecond AP, and wherein based on the value of the first update subfieldbeing set to 0, the multi-link probe response frame includes therequested partial information on the second AP.
 6. The method of claim2, wherein the profile field for the third AP further includes a secondupdate subfield, wherein based on a value of the second update subfieldbeing set to 1, the multi-link probe response frame includes onlyupdated information out of the requested partial information on thethird AP, and wherein based on the value of the second update subfieldbeing set to 0, the multi-link probe response frame includes therequested partial information on the third AP.
 7. The method of claim 2,wherein the multi-link probe response frame is configured based onvalues of the first and second Complete Profile Requested subfields. 8.A receiving multi-link device (MLD) in a wireless local area network(WLAN) system, the receiving MLD comprising: a memory; a transceiver;and a processor operatively coupled to the memory and the transceiver,wherein the processor is configured to: transmit a multi-link proberequest frame to a first AP; and receive a multi-link probe responseframe from the first AP, wherein the first AP operating on a first linkand a second AP operating on a second link are affiliated with an APmulti-link device (MLD), wherein the first non-AP STA operating on thefirst link and a second non-AP STA operating on the second linkaffiliated with a non-AP MLD, wherein the multi-link probe request frameincludes a profile field for the second AP, wherein the profile fieldfor the second AP includes a first Complete Profile Requested subfieldof a first STA Control field, wherein based on the first non-AP STArequesting partial information on the second AP, a value of the firstComplete Profile Requested subfield is set to 0, and wherein based onthe first non-AP STA requesting complete information on the second AP,the value of the first Complete Profile Requested subfield is set to 1.9. A method in a wireless local area network (WLAN) system, the methodcomprising: receiving, by a first access point (AP), a multi-link proberequest frame from a first non-AP station (STA); and transmitting, bythe first AP, a multi-link probe response frame to the first non-AP STA,wherein the first AP operating on a first link and a second AP operatingon a second link are affiliated with an AP multi-link device (MLD),wherein the first non-AP STA operating on the first link and a secondnon-AP STA operating on the second link affiliated with a non-AP MLD,wherein the multi-link probe request frame includes a profile field forthe second AP, wherein the profile field for the second AP includes afirst Complete Profile Requested subfield of a first STA Control field,wherein based on the first non-AP STA requesting partial information onthe second AP, a value of the first Complete Profile Requested subfieldis set to 0, and wherein based on the first non-AP STA requestingcomplete information on the second AP, the value of the first CompleteProfile Requested subfield is set to
 1. 10. The method of claim 9,wherein a third AP operating on a third link is further affiliated withthe AP MLD, wherein a third non-AP STA operating on the third link isfurther affiliated with the non-AP MLD, wherein the multi-link proberequest frame further includes a profile field for the third AP, whereinthe profile field for the third AP includes a second Complete ProfileRequested subfield of a second STA Control field.
 11. The method ofclaim 10, wherein based on the first non-AP STA requesting partialinformation on the third AP, a value of the second Complete ProfileRequested subfield is set to 0, and wherein based on the first non-APSTA requesting complete information on the third AP, a value of thesecond Complete Profile Requested subfield is set to
 1. 12. The methodof claim 9, wherein the probe request frame includes a first requestelement and a multi-link element, wherein based on the first non-AP STArequesting partial information on the first AP, partial information onthe first AP is requested based on the first request element, andwherein the profile fields for the second and third APs are included inthe multi-link element.
 13. The method of claim 9, wherein the profilefield for the second AP further includes a first update subfield,wherein based on a value of the first update subfield being set to 1,the multi-link probe response frame includes only updated informationout of the requested partial information on the second AP, and whereinbased on the value of the first update subfield being set to 0, themulti-link probe response frame includes the requested partialinformation on the second AP.
 14. The method of claim 10, wherein theprofile field for the third AP further includes a second updatesubfield, wherein based on a value of the second update subfield beingset to 1, the multi-link probe response frame includes only updatedinformation out of the requested partial information on the third AP,and wherein based on the value of the second update subfield being setto 0, the multi-link probe response frame includes the requested partialinformation on the third AP.
 15. The method of claim 10, wherein themulti-link probe response frame is configured based on values of thefirst and second Complete Profile Requested subfields.